Throughout the realms the Elves are equally renowned as among the greatest archers and wizards.  This, however, is not to deny that Elves have suffered military setbacks over the millennia as well.  Undoubtedly the most harrowing of these in recent memory was the Núlahlöa, often rendered as the “Occult Deluge” in the Common tongue.  During this cataclysmic event, a nefarious creature named Ras'guul Naf-Svengri (or simply the "Dark Overlord”) summoned a monsoon of ghastly minions from alternate planes of existence that enshrouded the Nine Elven Kingdoms in an epoch of unfathomable terror.  The overwhelmed and demoralized Elves soon found that they needed to forge new alliances, develop superior tactics, and discover new magical countermeasures if they were to prevail against this otherworldly assault.

Mystatherian Archery was but one of many such innovations, so named after the eponymous kingdom credited with first mastering this formidable martial art.  It is a systematic reform of the ancient tradition of Arcane Archery that synergizes melee, ranged, and mounted combat with spellcasting and other disciplines into a masterclass of combined arms operations.  While it favors lethality over artistry, and instills a greater emphasis on balancing adaptability and improvisation with tradition and regimentation, the essential concept of weaving magic into marksmanship remains undisturbed.  Its cruder aesthetics (if only by Elven standards) and iconoclastic fusion of Fey and non-Fey techniques were immediately greeted with extraordinary resistance; but its momentous debut in the glorious rout in the Keladyrian Forest reversed fortunes overnight and galvanized support from across the realms.  The raised siege at Aelithynia soon quelled all but the most parochial of critics, and the decisive Battle of the Bloodforge culminated in a final triumph on the Night of the Broken Chalice that saw the banishment of Ras'guul Naf-Svengri to the Lower Planes, his henchmen scattered or disintegrated, and the restoration of peace. 

To this day Mystatherian Archery continually evolves to address the needs of each generation, and to incorporate new technology and insights.  Its purest form is officially never taught to outsiders, though scholars steeped in history are possibly familiar with the name Andar Elarion.  This illustrious Elven warrior, later with the assistance of his Half-Elven protege, Faeryl Blackthorn, introduced a modified form to Faerun a mere century ago in order to adapt Mystatherian Archery to the aptitudes, limitations, proclivities, and temperaments of the shorter-lived races.  As before this too was cause for great controversy; the High King Lahrendal Renlathion initially protested with great offense at Andar's mere suggestion.  It was only much later--under the influential counsel of a swooning Princess Amyra and the duress of myriad calamities beset upon his domains in Ilynthymir, Taladyr, and Galaventyra--that the wise king reconsidered.  And, even then, the importation of Mystatherian Archery was only indulged a most reluctant blessing from Lahrendal and accompanied by a litany of stipulations. 

If an option requires a saving throw, your Mystatherian Shot save difficulty is as follows:  DC 8 + Proficiency Bonus + INT Modifier.

Restrictions: 
1)  Racial Secret:  The Mystatherian Archer is officially only eligible to Elves and highly trusted Half-Elves (see DM Notes below).
2)  Intellectual Aptitude:  Although this is a Fighter subclass, its rigorous study of magic is too burdensome for those of more modest intellectual capacity.  An Intelligence of 12 is required to become a Mystatherian Archer.
3)  Limited Multiclassing:  Because this martial art was developed in response to a crisis that threatened the elimination of all Elves, they refuse to offer training to Mystatherian Archers whom they cannot rely upon to dedicate themselves sufficiently to it.  For gaming purposes this means that any Mystatherian Archer must reach 7th level before taking on a new class, and anyone "dipping" into Mystatherian Archer must also reach 7th level before adding new levels in the original class.  Additionally any Mystatherian Archer who does multiclass must raise at least one level in Fighter for every one in their other class.  Wizards who become Mystatherian Archers are by far the most common, though the very rare Bard or Rogue are not entirely unknown.

DM Notes: 
1)  Racial Secret exceptions should require a major plot point in the campaign to justify training of an outsider (e.g., an orphaned Halfling newborn was adopted by Elves after the shire was wiped out by Drow marauders or a Dwarf who rescued an Elven princess and served as her as a personal bodyguard inside the Elven fortress for a century or two).  Perhaps also impose some additional restrictions, such as that outsiders can only use crossbows or thrown thrown weapons, or that the longbow is excluded from training.  Modifications may be needed to some abilities too (e.g., Immobilization Maneuver with a sling might be a concussive hit instead of a sling bullet lodging into the wall to pin the target; Bottomless Quiver could be a Reloading Sling or a Boomerang Axe or a Retrieving Javelin). 

2)  This subclass is, admittedly, an overcorrection to the underpowered Arcane Archer subclass, but this is intentionally done to counteract the power creep from WOTC because they understand that their new sourcebooks sell better when subclasses get progressively overpowered from earlier releases.  The archer will have more uses and more types of Arcane Shots with highly thematic buffs and descriptions to choose from.  Because It is easier for fellow DMs to simplify or scale back as they see fit than to imagine and weight everything from scratch--and then code this into DNDBeyond--I present things as is. 

3)  Even though I set a minimum intelligence for this subclass, I did not tie in the total number of shots or arrow options to a number + INT modifier as other homebrew revisions.  This was intentional so pure Fighters would not be limited any more than they already are in 5e, and to discourage most multiclassers.  The minimum Intelligence of 12 strikes a prudent balance between the competing concerns of limiting this to Fighters who will expend capital on this "dump stat" and not handicapping their martial attributes of Strength, Dexterity, and Constitution beyond recognition as a martial class.  Because the lore emphasizes that the Wizard was the natural partner of the Mystatherian Archer, it would make sense that some of those might end up cross-training enough to become multiclassers.  

4)  Just as with the subclass restrictions, the highly incremental progressions of abilities--especially in the layers of the Mystatherian Shot options--are all deliberate.  They serve to disincentivize any min-maxers tempted to "dip" into here only to leave when a lengthy gap in upgrades kicks in; to reward and motivate them to accumulate more levels; and to honor the lore of the subclass.  As long as things are consistently scaled in a highly organized manner, I find that players will tolerate a little more complexity if it means they have something to look forward to more often.  
 
5)  The Mystatherian Shot options are designed to be balanced (by 5e standards, anyway), but the balance is through situational parity akin to the fourteen clubs in a PGA golf bag than a myopic equality or plebeian equity.  Some of these arrows are incredibly versatile but not as powerful, while others dispense significantly more damage to justify having in one's quiver even though many creatures are immune to it; supplemental effects vary in duration or condition imparted; or their damage or conditions do not all register immediately; a few do not allow saves while others apply rarely used or two sets of saving throws; two even deal double damage in specific circumstances that more than compensate for deficiencies in other situations.  You also have all sorts of trick shot arrows that have no area of effect option, and some that do not confer additional or even base combat damage but provide debuffs, protection, knowledge, or otherwise reward creative and cooperative players.  Having so many choices for arrows in the quiver and the generous ability to swap two arrows each level will naturally preserve the lore's emphasis on versatility, flexibility, and experimentation as the archer anticipates and reacts to the changing needs of the unfolding campaign; and it will provide opportunities for players to pick selections simply for the flavor or narrative so that roleplaying is not reduced to power-gaming.  There are many more choices than in the original Arcane Archer, and they are all more powerful, but there will always be tough choices and many options left on the table.  Players should also be aware that, while the number of shots per day one can use appears much higher, the tradeoff is that short rests now only recover one shot.  I find that short rests are too easily abused or not always agreed upon by parties, so working with a daily total corrected this.  And since the supercharged area of effect Mystatherian Shots only recover on long rests, it's a rare chance for a martial class to target a cluster of adversaries without breaking the game.  It is simply too valuable to waste unless the encounter is threatening a total party kill or everyone is in desperate need of a long rest anyway.

6)  Based on recommendations elsewhere online, the hierarchy of damage types (and offsetting starting bonus damage) were arranged as follows:  Poison (6d6+ to offset extremely common immunity) --> Cold, Fire (5d6) --> Acid, Lightning (4d6) --> Necrotic, Psychic, Thunder (3d6) -->  Piercing, Slashing, Bludgeoning (2d6 with extremely reliable supplemental) --> Radiant (2d6 with powerful, but highly situational supplemental) --> Force (2d6 with versatile supplemental).  There is at least one arrow for every energy type except bludgeoning and slashing, and all of those damage type arrows have supplemental conditions.  These were always chosen by effects most consonant with the description of the arrow and its damage type, not by pairing the higher damage or better damage type with a weaker supplemental condition or vice versa.  The supplemental effects are always 3/4/5 rounds (initially/11th level/18th level) unless they are arrows who exchange the extra energy damage for an effect that lasts a minute as a spell (e.g., Blindness/Deafness, Charm Person, Ray of Enfeeblement, and Silence; Turn Fiends and Undead too) are instead for 5/6/7 because a round is listed as six seconds so this best balanced the actual spells and the incremental system of the other arrows with the relative abilities and limitations of Fighters and Wizards in terms (e.g., hit points, AC of Fighters vs Wizards; Mystatherian Shot totals vs. spell slots; superior group effects of spell versions).  Because the two bonus piercing damage arrows have powerful mechanics to hit and piercing damage is rarely resisted, they received no supplemental effect.  And because the Arrow of Ribaldry is explicitly ends if combat ensues and corresponds most closely to the hour-long Charm Person spell, the effects were uniquely lengthy. 

7)  The order for the Mystatherian Shots is not alphabetical.  Instead the first ten (A-I) are in ascending order according to damage type hierarchy, with the exception of the two piercing bonus arrows being kept separately due to their unique characteristics (K, L).  The next four (M-P) are all debuffing arrows similar to Wizard spells.  The second half (M-W) serve various other utility functions and can be subdivided into divination (Q, R), defensive (S, T, U), and roleplaying versatility (V, W).  These five utility options all initiate with a brief introduction to the lore behind their development and applications.

ARCANA SKILL PROFICIENCY:

Thorough understanding of the history of magic and its symbols and traditions, as well as of the nature of the planes of existence and the creatures populating them, are indispensable prerequisites for admission into the academies training candidates in Mystatherian Archery.  You gain proficiency in the Arcana skill if you do not already possess it.

MAGIC ARROW:

At 3rd level whenever you fire a nonmagical arrow, you can make it magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.  The magic fades from the arrow immediately after it hits or misses its target.

MYSTATHERIAN SHOT:

At 3rd level you learn to unleash special magical effects with some of your shots.  Select three Mystatherian Shot options.  Once per turn when you fire an arrow you can apply one of your Arcane Shot options.  You decide to use the option only after the arrow hits (unless the option doesn’t involve an attack roll).  Additional choices are gained at 4th, 5th, 8th, 13th, 14th, 16th, 17th, and 19th level.  Two shot options can be swapped out at each level raised.

The Mystatherian Shot can be used three times per day.  One additional usage is also gained at 6th, 9th, 12th, 15th, and 18th level.  One shot is recovered after a short rest, and all are recovered after a long rest.

The 10th level area of effect is able to be used once per long rest, twice at 15th, and thrice at 20th level.  Short rest never recovers the area of effect option.

A) Venomous Arrow:

Dripping with the adulteration of necromantic magic, the moment Venom Arrows sink their steely teeth into their quarry, they administer an additional 2d6 of poison damage.  Their virulence swells to 3d6 at 11th level and an even more lethal 4d6 at 18th level.  A successful Constitution saving throw halves both the initial and subsequent damage, but a failure also transmits a poisoned condition that lingers indefinitely.  Poisoned creatures suffer disadvantage on all of their attack rolls and ability checks.  Because the venom yielded from these arrows is such a potent cocktail of neuro-, hemo-, and cytotoxins, their bite inflicts an additional 2d6 of poison damage (this delayed damage does not also scale) every round thereafter until the target is cured or dies.  A Medicine skill check can be attempted once per round (not per turn), but with disadvantage to neutralize the poison due to its magical enrichment and exceptional complexity.  Your archer can also opt to inject the arrows with delayed onset variants of 5, 30, 60, or 240 minutes.  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

B) Frostbite Arrow:

Sheathed in transmutation magic, these glassy arrows precipitate a blizzard of icy shards upon their adversaries for an additional 5d6 of cold damage.  This bombardment further accumulates to 6d6 at 11th level and an abominable 7d6 at 18th level.  A successful Dexterity saving throw halves the damage, but a failure indicates that their chilled bones and shivering spines from the ensuing avalanche of hyperborean pangs has frozen them in their tracks, hence they also suffer the restrained condition for three rounds.  This escalates to four rounds at 11th level and five rounds at 18th level.  Restrained creatures have a movement of 0 and disadvantage on their Dexterity saving throws.  Restrained creatures also suffer disadvantage to their attack rolls, while attack rolls against them enjoy advantage.  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

C) Scorching Arrow:

A spark of transmutation magic ignites your arrows, presenting a halo of flickering flames that torches enemies for an additional 5d6 of fire damage.  This combustion blazes to 6d6 at 11th level and an infernal 7d6 at 18th level.  A successful Dexterity saving throw halves the damage, but the terrifying sight and acrid odor of one's own incinerated flesh also forces a Wisdom saving throw to avoid the frightened condition for three rounds.  This mounts to four rounds at 11th level and five rounds at 18th level.  Frightened creatures receive disadvantage on all ability checks and attack rolls while the source of their fear remains in their line of sight.  They also cannot willingly move closer to the source of their fear (but they can to allies of the source).  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

D) Lightning Arrow:

The electromagnetic power of evocation magic courses through your arrows.  When you discharge these crackling bolts of scintillating energy, they provoke violent convulsions that seize muscles and rattle bones for an additional 4d6 of lightning damage.  This writhing agony surges to 5d6 at 11th level and a cardiac-arresting 6d6 at 18th level.  Damage is also doubled for those jounced while donning metal armor or in contact with similar quantities of conductive materials.  A successful Dexterity saving throw halves the damage, but a failure also confers the blinded condition for three rounds while recovering from the spectacular flash of lightning.  This jolts up to four rounds at 11th level and five rounds at 18th level.  Blinded creatures automatically fail any ability check requiring sight, have disadvantage on their own attack rolls, and must endure advantage on all attacks to them.  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

E) Corrosive Arrow:

Through evocation magic you suffuse your arrows with a caustic oil that quickly dissolves flesh, bone, and most other substances it besmirches for an additional 2d6 of acid damage.  This initial acid damage strengthens to 3d6 at 11th level and an overpowering 4d6 at 18th level.  Its exceptional viscidity precludes any attempt to remove it with neutralizing chemicals, towels, or water (but Dispel Magic will work) before a second round of 2d6 in acid damage occurs (this delayed damage does not also scale).  While the excruciating pain may emotionally scar as it physically disfigures, its magically enhanced corrosive effect is prudently engineered to automatically self-neutralize after the second round in order to minimize collateral damage to the environment or any valuable treasure.  A successful Dexterity saving throw halves the initial and residual damage, but a failure also sustains the paralyzed condition for three rounds due to a state of shock from the intolerable pain.  This compounds to four rounds at 11th level and five rounds at 18th level.  Paralyzed creatures cannot move or speak (their blood-curdling screams and torturous involuntary spasms notwithstanding), and they automatically fail all Strength and Dexterity saving throws.  Opponents attack with advantage, and any hits are automatically critical hits if they are made within five feet of the paralyzed creatures.  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

F) Vampiric Arrow:

These sepulchral arrows are tinged with necromantic magic that drains the life force of their targets for an additional 1d6 of necrotic damage on the initial round.  The deterioration festers to 2d6 at 11th level and a gangrenous 3d6 at 18th level.  As the sorcery plunges deeper into sinew, Vampiric Arrows callously wither the poor soul to a husk for an additional 1d6 damage over the next two rounds (this delayed damage does not also scale).  A successful Wisdom saving throw halves both the initial and subsequent damage, but a failure also yields an immediate condition of level 1 exhaustion (ability checks with disadvantage) that deteriorates to level 2 exhaustion (speed is halved) on the next round, level 3 exhaustion (disadvantage on all attack rolls and saving throws) on the third round, and lapses into a persistent state of level 4 exhaustion (hit point maximum is halved) from the fourth round on.  These enervating effects remain until either magically healed (e.g., by Greater Restoration) or a long rest.  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

G) Entrancing Arrow:

Weaving enchantment magic into your arrows, these nightmarish implements do not simply physically wound, but also psychologically damage and beguile their victims.  An additional 3d6 of psychic damage befalls these wretches, and this torment intensifies to 4d6 at 11th level and a stupefying 5d6 at 18th level.  The enchantment magic also leverages this horror through trauma-based mind control into temporarily reprogramming those deranged into actually serving the source of their misery.  A successful Wisdom saving throw halves the damage, but a failure also imposes the charmed condition for 30 minutes (not rounds).  This duration lengthens to 45 minutes at 11th level and 60 minutes rounds at 18th level.  Charmed creatures cannot attack the charmer or its allies in any way, including by the use of harmful abilities or magical effects; and the charmer (but not its allies) enjoys advantage on any ability check to interact socially with them.  All charmed effects end if the charmer or its allies attack or otherwise damage them (e.g., the charmed is accidentally knocked from a high ledge or becomes collateral damage from a tossed oil flask), or else forces them to make any saving throw (e.g., a Dexterity saving throw to avoid a crashing chandelier when the archer's ally severs the support ropes).   At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  When the effects end, the creature knows it was charmed by you.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level. 

H) Thunderclap Arrow:

Forged with evocation magic, Thunderclap Arrows incapacitate foes with an earsplitting blast of sonic energy for an additional 3d6 of thunder damage.  These shock waves amplify to 4d6 at 11th level and a krakatoan 5d6 at 18th level.  A successful Dexterity saving throw halves the damage, but the target must also pass a Constitution saving throw to avoid receiving both the stunned and deafened conditions for three rounds while thunderstruck by the interminable clangor.  This cranks up to four rounds at 11th level and five rounds at 18th level.  Stunned creatures cannot move, can only speak falteringly, and automatically fail all Strength and Dexterity saving throws.  All attack rolls by opponents are also made with advantage.  Because stunned creatures are, by definition, also incapacitated, they also cannot take any actions or reactions (including attacks).  Deafened creatures automatically fail any ability check that requires hearing.  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

I) Soulcrusher Arrow:

Your scrupulous command of evocation magic permeates these arrows with a glorious aura of mystical brilliance.  A preternatural fire sublimates these reprobates with an additional 2d6 of radiant damage.  This resplendent searing magnifies to 3d6 at 11th level and an incandescent 4d6 at 18th level, though enemies sniped by the Soulcrusher Arrow can halve the damage with a successful Wisdom saving throw.  When unleashed upon fiends or undead, the damage meted out is doubled to 4d6, and all of such in a straight line of up to 30 feet from the target who fail the saving throw are also turned for five rounds.  This soars to six rounds at 11th level and seven rounds at 18th level.  Turned creatures must spend their turns trying to move as far away from you (but not your allies) as possible, and they cannot willingly move to any space within 30 feet of you.  While turned they also cannot take reactions, and for their regular action they can only either dash or try to escape from an effect that prevents them from moving.  At 10th level your archer can choose at the time of attack to affect anyone in a five foot radius from the target.  Notice that all the other spells start out with no straight line area of effect of up to 30 feet and then grant this at 10th level, while this Soulcrusher Arrow instead begins with this effect and upgrades at at 10th level to a five foot radius area of effect.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

J) Vector Arrow:

This fistful of evocation magic simultaneously wallops foes and manipulates battlefields to your strategic advantage as blast waves pulverize anything in their wake with an additional 2d6 of force damage.  This concussive impact expands to 3d6 at 11th level and an obliterating 5d6 at 18th level.  Targets sized Medium or Large are impelled by this barometric burst to move up to ten feet in any direction and distance you choose.  Two saving throws are then attempted.  A successful Strength saving throw halves both the damage and forced movement.  Regardless of that result, a Dexterity saving throw is next attempted to determine if the target falls into the prone condition for three rounds.  Prone creatures can only move by crawling unless they stand up to end the condition, and they suffer disadvantage on attack rolls.  Opponents attack with advantage within five feet of them, but actually attack with disadvantage beyond five feet past due to the effect of cover afforded to anyone lying down, regardless of the reason.  At 11th level the force damage and distance inflates to 3d6 with 20 feet of vectoring and the prone condition lasting four rounds.  This is later expanded to 4d6, 30 feet of vectoring, and five rounds prone at 18th level.  The distances always double from the listed rate for size Tiny or Small creatures, and always halves for size Huge, while Gargantuan creatures are never vectored or knocked prone.  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

K) Chain Strike Arrow:

Artful manipulation of transmutation magic endows these ethereal arrows with the capacity to mystically penetrate and sequentially dispatch all assailants in their path.  When you use this option, you do not make an attack roll.  The arrow instead hurtles forward in a straight line that is one foot wide and 50 feet long, and passes it harmlessly through all physical objects and energy sources it encounters, ignoring all cover (1/2, 3/4, full) before vanishing.  Each creature in that line that the archer intends to take damage must attempt a Dexterity saving throw.  Success halves damage, but a failure causes an additional 2d6 of piercing damage that accelerates to 3d6 at 11th level and peaks at 4d6 at 18th level.  At 10th level your archer can fire two Chain Strike Arrows in the same attack once per day.  This scales to three arrows in the same attack and two uses per day at 15th level, and then to four arrows and three uses per day at 20th level.  This option only recovers on long rests regardless of level.  Any countermeasures (e.g., the Mystatherian Archer's Counterstrike Arrow) only deflect or absorb the damage from one arrow even if they are aimed at the same target.

L) Stalking Arrow:

Fortified with divination magic, these Stalking Arrows hunt down even the most elusive of foes like wounded prey.  When utilizing this particular arrow, you do not roll for an attack.  Simply choose one creature you have seen in the past minute--even if it is now invisible.  The arrow locks onto the target, ignoring 1/2 and 3/4 cover, and automatically reaches it (regardless of twists and turns or heights and drops) as long as it remains within the arrow’s maximum range and carves a path wide enough to slip through.  If those conditions are met, the arrow automatically hits, along with an additional 2d6 of piercing damage that is sharpened to 3d6 at 11th level and honed to 4d6 at 18th level.  The target attempts a Dexterity saving throw to halve the damage, but if it fails the target also reveals to the archer its new location (if hidden) and its invisibility is dispelled.  The arrow vanishes whenever its maximum range is exceeded.  At 10th level your archer can fire two Stalking Arrows in the same attack once per day.  This scales to three arrows in the same attack and two uses per day at 15th level, followed by a further improvement to four arrows and three uses per day at 20th level.  This option only recovers on long rests regardless of level.  Any countermeasures (e.g., the Mystatherian Archer's own Counterstrike Arrow) only deflect or absorb the damage from one arrow even if they are aimed at the same target.

M) Retarding Arrow:

A dynamic synthesis of transmutation and necromancy, these degenerating arrows can both physically cripple and mentally disable hapless victims in a single strike.  While no supplemental damage is included with the base arrow damage, a failed Wisdom saving throw will force the afflicted creature to experience all the deleterious effects that are identical to the Slow spell, albeit for a shorter duration.  These are as follows:  -2 to AC; -2 to Dexterity saving throws; it cannot use reactions; on its turn it can either use an action or a bonus action, not both; and, regardless of the creature’s abilities or magic items, it cannot make more than one melee or ranged attack on its turn.  If the creature attempts to hurl a spell with a casting time of 1 action, roll a d20.  On an 11 or higher, the spell does not take effect until the creature’s next turn, and the creature must use its action on that turn to complete the spell.  If it cannot do so, the spell is wasted.  The accompanied mental component is disadvantage on all Intelligence and Wisdom saving throws and ability checks.  Success on the saving throw staves off all these effects, but it does not halve the arrow's base damage.  A single Dispel Magic will remove both the physical and mental effects too, but these effects otherwise all last for five rounds.  They are prolonged to six rounds at 11th and seven rounds at 18th level.  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

N) Enfeebling Arrow:

Your necromancy-laced arrows sap the target’s vitality and cripple its movement similar to the Ray of Enfeeblement spell.  While no supplemental damage is appended to the base arrow damage, a failed Constitution saving throw will cause the target to deal half damage on all of its own attacks.  Its movement is also reduced to 1/4.  A successful one excludes both these effects, but it does not halve the base damage.  Each effect lasts for five rounds and advances to six rounds at 11th level and six rounds at 18th level.  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

O) Luring Arrow:

Imbued with a broad spectrum of enchantment magic distilled from a comprehensive examination of their bestiaries, the Elves crafted the Luring Arrows to mitigate the home terrain advantages strategized by the most cunning and elusive monsters.  Whether they be dive-bombing dragons or skyscraping wyverns, arboreal rajangs or aquatic abeloths, tunnel-boring umber hulks or wall-scaling driders, the arrows effectively coerce the grounding, emersion, teleportation, or other form of relocation to the 'same surface level'*** as the archer.  Only the ordinary base damage of the arrow is applied, but a Wisdom saving throw to resist this compulsion is attempted with disadvantage--even creatures immune to charm are reduced to resistance, and those resistant drop to only rolling a single die.  If that Wisdom save is successful, the target rebuffs the command., but a failure obliges it to recklessly disregard tactical positioning and other considerations as it is forced to initiate its relocation to the same surface level within 1d4 rounds and find a spot within 300 feet of the archer.  The surface level and distance are determined from the final position of the archer during the conclusion of its turn in the round the arrow is fired.  The target will then be unable to escape the defined surface level for five rounds, but every movement type it possesses (e.g., climbing, burrowing, swimming, and flying) remain unaltered.  It does not know it was charmed until after its effects wear off.  This duration increases to six rounds at 11th level and then seven rounds at 18th level.  At 10th level your archer can choose at the time of attack to affect anyone in a 10 foot radius from the target.  This widens to a 15 foot radius at 15th level and a 20 foot radius at 20th level.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

***DM Notes:  'Same surface level' requires further elaboration.  In the case of underwater combat or other unusual terrain, the archer may choose to define this in some other DM-approved fashion (e.g., if the combat occurs at the ocean floor, the arrow could compel sea creatures escaping to the surface or diving into a deep-sea trench to return to the ocean floor; or an archer perched on a canyon rim could induce a chimera flying beneath its feet to be 'grounded' by actually flying to higher ground to land on the same crag).  Because natural terrain is almost never truly level, the arrow's requirements are met so long as the archer and target are sufficiently level to where no high/low ground combat modifiers apply.  If this cannot be avoided, the creature would still snatch up that high ground.  But the creature could also be trapped by a lack of valid options into ceding the high ground or relocating to a laid trap or active area of effect spell even though the arrow cannot actually order this location, much less modify the creature's behavior in any other way.  A wounded creature would likely avail itself of the 300 feet maximum distance, but if it is protecting its master or hatchlings, or if ascertains that it could wipe out the party, the creature would still land within striking range and press the attack while grounded.

P) Hermetic Arrow:

An appalling concoction of necromancy entombs your impaled enemies in virtual chambers of sensory deprivation.  While the arrows only provide the base arrow damage, they severely burden victims with a half-dozen debilitating conditions as if they were hermetically sealed from all external stimuli.  This means they are (1) blinded, (2) deafened, and (3) incapable of communication through sound as if mute, though telepathy still works.  And they also suffer (4) anosmia, (5) ageusia, and (6) anaphia.  While blinded and deafened, the blighted automatically fail any ability checks that require sight or hearing, and opposing attack rolls have advantage while theirs suffer disadvantage.  Nor can they use darkvision or see through darkness without magical illumination.  Blindsight and truesight overcome this, but not tremorsense in this case due to the concomitant anaphia.  Because D&D is limited in describing these latter three conditions, the DM may rule on what applies, but wherever a penalty does it should consist of an automatic failure of checks based on the sense of smell, taste, and touch.  Without question, however, the anosmia negates the "keen smell" (e.g., in wolves and tigers), and the anaphia negates the tremorsense ability (e.g., in earth elementals and purple worms).  Tracking scents or detecting spoiled or toxic substances should no longer be possible while the arrow's effects remain.  On the other hand, affected creatures should also temporarily behave differently from not experiencing the pain, much like the villain Renard in the James Bond movie The World is not Enough.  Thus, while they should still lose hit points from thunder damage, they might not flee since they cannot perceive the pain, see any wounds, or even hear their allies imploring them to retreat.  Dispel Magic eliminates all six symptoms simultaneously.  There is no saving throw available to prevent these effects, and they all last for five rounds.  This aggravates to six rounds at 11th level and seven rounds at 18th level.  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

Q) Mindbender Arrow:

These spectral arrows are encased in divination magic to pierce the minds as they thrust into the bodies of your nemeses to gain an ephemeral glimpse into their most confidential thoughts.  The mechanics differ from the Detect Thoughts spell, but fulfill the same essential purpose.  You forfeit your arrow's base damage, exchanging for it an instantaneous gaze into the target’s mind with no saving throw to resist.  All surface thoughts are immediately revealed (e.g., what is most on its mind at the moment).  On the next round after the attack, the target can attempt a Wisdom saving throw to resist further probing.  If it succeeds the mental intrusion ends, but if it fails you learn one deeper insight about its reasoning, emotional state, or whatever weighs on its mind.  Examples include its political aspirations or phobias; something it worries over, loves, or hates; a favorite battle tactic or spell; its assessment of the morale and loyalty of its minions; thoughts on a magic item it desires or possesses; the location of hidden tunnels, trap doors, or hostages; or perhaps an embarrassing secret, a murder plot, or an ambush planned in the mountain pass.  For each round you attempt to rummage through its mind after that, the creature may use its action to make an opposing Intelligence check.  If its opposing roll beats yours, the mindbending ends altogether with no new questions possible, but each failure permits a new question to be asked on your subsequent turns up to a maximum of five times or until your first lost contested roll.  This extends to six rounds at 11th level and seven at 18th level.  Unless the differential is very high (e.g., 10+), the creature may not ever directly answer your scrutinizing questions as if it were unraveling before a police interrogation.  But it will utterly recoil at the mind-wrenching experience of having its thoughts and memories leafed through like index cards in a Rolodex.  The spine-chilling auditory sensation of your imposing voice penetrating its mind and reverberating from inside its own skull will then strip bear its internal dialogue.  Any attempt to ignore or filibuster your inquiries will ineluctably shape its consequent thoughts, thereby permitting your extrication of the answers in due course.  A maximum of five insights over five rounds is possible to start, but this inflates to six at 11th level and seven at 18th level.  Creatures with an Intelligence of 3 or lower or that do not speak any language are unaffected and yield no information.  At 10th level your archer can choose once per day at the time of attack to extricate the surface thoughts of any creature within 15 feet of the original target before determining which one merits further probing.  This scales to 30 feet and twice per day at 15th level, and to 40 feet and three times per day at 20th level, but it also only recovers on long rests regardless of level.  Throughout this mental assault, the target can also sense the intrusion, but the arrows are invisible to anyone not bearing Truesight.  Unless it can spot you after the attack, recognizes your voice, or could deduce your identity from the questions alone while being psychically interrogated, it will only become aware of the general direction of its origination--just as it would from being hit by any other arrow.

R) Metastrike Arrow:

Harnessing innovative divination magic, your arrows tap into the very essence of your adversaries to facilitate your apprehension of some aspect of their nature.  When rolling for your normal base damage for your arrow (there is no supplemental damage effect), roll an additional d100 to determine precisely which feature you learn.  The target has no saving throw, and no resistance or immunity applies to limit this either.  Re-roll if there is no information of the type rolled.  At 11th level two dice rolls are made to discover twice as much about the target.  This divination magic is later bolstered to three separate dice rolls at 18th level.  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It only recovers on long rests regardless of level.  Because the same d100 rolls apply to everyone in that line, there is no separate d100 roll for each target; nor can you decide after a disappointing d100 roll that you do not want to expend your usage of the area of effect version.

D100 Roll:
01-05:  Speed at one movement type (e.g., burrowing, climbing, flying)
06-10:  One ability score
11-15:  One saving throw
16-20:  One skill (e.g., stealth check, weapon proficiency)
21-25:  One vulnerability
26-30:  One resistance
31-35:  One immunity
36-40:  Passive Wisdom score
41-45:  One special sense (e.g., blindsight, tremorsense)
46-50:  One special trait, action, reaction, or ability (e.g., a lich’s spellcasting; bugbear’s surprise attack)
51-55:  One language (e.g., Celestial, Undercommon, use of telepathy)
56-60:  XP
61-65:  Challenge Rating
66-70:  One action (e.g., multiattack of 3x/rd, surprise)
71-75:  One legendary action or regional effect (e.g., dragon in its lair) (if any)
76-80:  Armor Class
81-85:  Hit Points, total 
86-90:  Hit Points, current
91-95:  Class levels, total (if any)
96-00:  Fighter Class, total (if any)­

S) Counterstrike Arrow:

The catastrophic failure during the early phases against Dark Overlord Ras'guul Naf-Svengri and his eldritch allies were rightfully attributed to a troubling deficit in the Arcane Archer's defensive capabilities.  Along with the Dispelling Arrow, this Counterstrike Arrow furnished an enormous contribution in surmounting the Occult Deluge.  It is heavily clad in layers of highly efficacious and seemingly prescient abjuration magic to foil incoming attacks.   Whenever a creature within your bow's range is about to hit a target with a ranged attack, you can use your reaction to make a contested attack roll.  If your attack roll is equal to or higher than the initial attack roll, the entire damage from the attack is parried.  But if you roll lower, you still deflect 2d6 damage.  This later sharpens to 3d6 at 11th level and 4d6 at 18th level.  At 10th level the archer can fend off melees attack as well.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.  You can still use this Counterstrike Arrow as a reaction even after you have taken a combat action that used a Mystatherian Shot--including a previous Counterstrike Arrow.  Declaration of usage must occur before damage is rolled (or at least revealed, if rolled simultaneously with the attack roll). 

T) Dispelling Arrow:

During the Siege of Aelithynia, the Elves were served a painful reminder of the relative values between prevention and remedy.  Lessons learned from that horrendous ordeal catalyzed a renewed interest in the heretofore neglected school of abjuration magic.  This Dispelling Arrow was a pivotal advancement to Arcane Archery by the Mystatherian Elves.  Its arrows are capable of instantaneously and unerringly neutralizing any Cantrip, 1st, or 2nd level spell targeting a creature, object, or magical effect within range without having to make an attack roll.  For instance an object can be targeted to reverse a Levitation spell cast upon it.  Or Stinking Cloud spell can be eliminated by striking one square of the sprawling noxious gas's area of effect.  Even though it is not spectral in nature, this arrow generates no combat damage because it is so thoroughly drenched in abjuration magic.  This is by design so that no harm befouls an ally tagged by one of these missiles while purging it of undesirable effects.  Its dispelling proficiency upgrades to allow for 3rd level spells at 11th level and 4th level spells at 18th level.  There is no saving throw possible for an opponent to overrule the dispelling effect.  At 10th level your archer can choose at the time of attack to either affect anyone in a straight line of up to 30 feet from the target or to dispel two separate instances of spells causing adverse effects on a single target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

U) Teleportation Arrow:

Born out of the necessity of rapid egression from perilous combat, resourceful Mystatherian Archers promptly deployed these Teleportation Arrows to scale fortress walls and mountain cliffs, circumvent rapids, and outflank, pursue, or corner routed enemies.  By an ineffable exploitation of Conjuration magic, your corporeal and spiritual essence establishes a temporary ontological bond with the arrow that enables you to teleport to the location where it lands.  Any spot within 30 feet is DC 5, and for every 30 feet thereafter the difficulty increases by 5.  The maximum intended target of teleportation is always 300 feet of teleportation regardless of level or bow type, but this may be exceeded on overshots.  A DC 0 means a roll is no longer even needed, not that only natural 1's miss.  At 10th level and again at both 15th level and 20th level, the difficulties reduce for each range by 5 (see table below).  Arrows that miss their spots land one random square away for every 5 the attack roll misses by, and in a direction from that spot determined by using a 1d8 if using square grids and 1d6 if hex grids.  On ricochets the final landing spot determines effects, not the ricochet point.  If the arrow lodges into a wall, the archer relocates to the nearest square while suffering 2d6 of force damage from the metaphysical shock of teleporting to an invalid location.  If the arrow embeds into the ceiling, your archer lands directly below the high spot while incurring both the 2d6 of force damage and the calculated falling damage (1d6 per 10 ft/max 20d6).  And if the arrow hits another creature, the same 2d6 of force damage applies to the archer, but the struck creature only receives the arrow damage.  At 11th level your archer can choose at the time of attack to also teleport a single passenger of Size Large or Medium (or two of Small or Tiny).  Twice as many can be escorted at 18th level.  Any accompanying individuals must use their reactions to reach out and touch the archer to also be teleported, and they always remain in the same relative position in the new location (e.g., if one square to the left of the archer before teleportation they remain on that side).  They also receive all force and falling damage from teleportation whenever the archer does.  This passenger teleportation option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

Recommended Base DC for Teleporting Ranges (Presuming Clear Shot):
000 - 030 ft   =  DC 05 (DC 00/10th level, DC 00/15th level, DC 00/20th level).
030 - 060 ft   =  DC 10 (DC 05/10th level, DC 00/15th level, DC 00/20th level).
061 - 090 ft   =  DC 15 (DC 10/10th level, DC 05/15th level, DC 00/20th level).
091 - 120 ft   =  DC 20 (DC 15/10th level, DC 10/15th level, DC 05/20th level).
121 - 150 ft   =  DC 25 (DC 20/10th level, DC 15/15th level, DC 10/20th level).
151 - 180 ft   =  DC 30 (DC 25/10th level, DC 20/15th level, DC 15/20th level).
181 - 210 ft   =  DC 35 (DC 30/10th level, DC 25/15th level, DC 20/20th level).
210 - 240 ft   =  DC 40 (DC 35/10th level, DC 30/15th level, DC 25/20th level).
241 - 270 ft   =  DC 45 (DC 40/10th level, DC 35/15th level, DC 30/20th level).
271 - 300 ft   =  DC 50 (DC 45/10th level, DC 40/15th level, DC 35/20th level).

V) Auxiliary Arrow:

Occasioned by the Occult Deluge, this Auxiliary Arrow is a marvel of transmutation magic that almost singlehandedly wrought victory at the Battle of Bloodforge by synergizing the Mystatherian Archer's powers with those of the Elven spellcasters who stood beside them on the rearguard.  These tremendously versatile tools are capable of storing and transferring the effects of any Cantrip or spell up to 5th level by any full- or half-casting class.  Doing so allows the tandem to extend the reach of touch-based spells, to more profitably determine the initiation point of area of effect spells, and to circumvent other limitations (e.g., the wizard cannot see the target as the spell requires, but the archer can).  The magic bestowed upon the arrows is so thoroughly refined that the base materials of the arrows are no longer capable of penetrating anything they strike, hence there is never any resulting combat damage.  A regular hit versus AC is required to hit creatures.  The DM will determine the difficulty of hitting a spot (e.g., as posted below) and adjusting for tricky lofts, obstructions, etc.  Any saving throws and effects dependent upon the spellcaster’s proficiency still rely upon that spellcaster’s modifiers, not the archer's.  The transferring power is augmented to allow for 6th or 7th level spells at 11th level, and even to 8th or 9th level spells at 18th level.  At 10th level your archer can choose at the time of attack to store the spell one round.  This increases to two rounds at 15th level and three rounds at 20th level.  Only one spell can ever be stored at a time.  This option is available only once per day, but it scales to two rounds at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.  The ready action may be utilized while waiting for the spells to be loaded, as can the dash action while the arrow is loaded with a spell.  If the Auxiliary Arrow is not launched after the permitted round delay, the spell is lost.  The archer also receives force damage totaling 1d6 per spell level stored (e.g., an 8th level Wizard spell is 8d6 in force damage).  A Constitution saving throw halves the damage, but the bow and quiver are both vaporized by the implosion, along with any stored arrows in the quiver with no saving throw to resist. 

Recommended Base DC for Auxiliary Arrow Ranges (Presuming Clear Shot):
000 - 030 ft   =  DC 05 (DC 00/10th level, DC 00/15th level, DC 00/20th level).
030 - 060 ft   =  DC 10 (DC 05/10th level, DC 00/15th level, DC 00/20th level).
061 - 090 ft   =  DC 15 (DC 10/10th level, DC 05/15th level, DC 00/20th level).
091 - 120 ft   =  DC 20 (DC 15/10th level, DC 10/15th level, DC 05/20th level).
121 - 150 ft   =  DC 25 (DC 20/10th level, DC 15/15th level, DC 10/20th level).
151 - 180 ft   =  DC 30 (DC 25/10th level, DC 20/15th level, DC 15/20th level).
181 - 210 ft   =  DC 35 (DC 30/10th level, DC 25/15th level, DC 20/20th level).
210 - 240 ft   =  DC 40 (DC 35/10th level, DC 30/15th level, DC 25/20th level).
241 - 270 ft   =  DC 45 (DC 40/10th level, DC 35/15th level, DC 30/20th level).
271 - 300 ft   =  DC 50 (DC 45/10th level, DC 40/15th level, DC 35/20th level).

W) Ribaldrous Arrow:

These mischievous arrows are an amalgamation of illusion and enchantment magic devised by Gnomes, Halflings, or possibly even planes-wandering Kender—the lore is confused here—and infamously introduced to Mystatherian Archers at the most inopportune occasion in celebration of the 500th anniversary of the Night of the Broken Chalice.  Due to its illusion magic, these Ribaldrous Arrows are spectral in nature, imperceptible without Truesight, and supply no combat damage; but any fellow unfortunate to have been struck by one may thereafter only regret--never doubt--either their existence or the veritable catalog of socially awkward conditions the bewitchment entail... all for the amusement of bystanders!  Success on a Wisdom saving throw wards off all effects, and the usual charm resistances and immunities apply; but a failure induces effects of a relatively benign nature to be selected or invented by the archer at the DM's discretion.  They cannot cause the charmed individual to intentionally harm itself, but the charmed may still do so in an unintentional, indirect, and inconsequential manner (e.g., a sneezing fit might happen to cause broken capillaries, and it might want to put foreign objects in its nose for an impression of a walrus, but it would not try to cause a bloody nose; or the individual might be charmed into becoming clumsy and inebriated, and might even get into a scrum after spouting insults or an inadvertently spilling another patron's ale, and it might even try to pick a fight of its own volition, but it could not be charmed into picking the fight against its own judgement like other charm spells).  The DM may decide to impose disadvantage or even advantage to skill checks or conditions while the target is under this arrow’s influence, but if combat ensues the jolt of adrenaline accompanying the conflagration invariably shakes off any combat-related effects after exactly one round. 

Connoisseurs of such shenanigans have witnessed innumerable effects over the decades since its creation.  Although no comprehensive list is in public circulation, the following may be considered fair game:  Uncontrollable flatulence, revolting breath, or putrid body odor; a bout of coughs, hiccups, or sneezes; spontaneous conjunctivitis, the ringing of tinnitus, or a ‘hot ear’ that urgently requires misting; teeth that visibly and audibly trill like piano keys whenever the subject speaks; copious drooling at the sight of the innkeeper's homely daughter; impossibly overactive tear ducts triggered whenever the victim is eating; a sudden, very specific phobia of a ridiculous nature (e.g., the coarse hair on a Halfling feet; hearing odd numbers whispered in Dwarvish) or comical delusion (e.g., claiming to be a werewolf; sliding on the ground while convinced to be slowly metamorphosing into a slug); the compulsion to brandish one's 'air lute' skills while reciting an epic poem or singing a ballad off-key; victims have also been spotted crafting colorful limericks, roasting their lords with surprisingly eloquent profanity, and even lampooning the accents and mannerisms of foreign dignitaries. 

The single effect lasts 30 minutes (not rounds), but the archer may instead choose two simultaneous or staggered effects for 15 minutes each.  At 11th level a third effect may be distributed evenly from 45 minutes, and at 18th level up to four effects spanning 60 minutes may be utilized for your diversion.  At 10th level your archer can choose at the time of attack to affect anyone in a straight line of up to 30 feet from the target.  This option is available only once per day, but it scales to two times per day at 15th level and three at 20th level.  It also only recovers on long rests regardless of level.

BOTTOMLESS QUIVER:

At 7th level your Mystatherian magic binds your bow to your quiver, and they to you.  You wield an unlimited supply of nonmagical arrows and can still store up to 20 magical or DM-required specialized nonmagical arrows in your quiver.  With each drawing of your bow, a new arrow of any kind in that quiver will instantaneously materialize nocked to your string, and by mental command the magical or nonmagical ones will all possess the requisite specialized tips and shafts as needed.  This includes but is not limited to deeply barbed or unbarbed arrows; frog-crotch, treble, and anchor-head tips; blunt or suction tips; and shafts with sleeves for affixing messages, cable, or rope.***  The Bottomless Quiver ability cannot be removed by Dispel Magic, Banishment, or other spell, but if either the bow or quiver is lost or stolen, a long rest must be taken to ontologically rebind the archer with the replacements.  While anyone can use the bow and the 20 arrows, not even fellow Mystatherian Archers can use their abilities on them until replacing the archery equipment's bond with their own during a long rest.

***DM Notes:  Because this ability is largely about minimizing the tedium of keeping track of arrows for a character so dependent upon them and not a Bag of Holding, certain tips should not be permitted or should at least require extra preparation time to offset any potentially game-breaking advantage.  For instance the ability to spam pre-poisoned or flaming arrows, or to have an endless supply of torches for light and heat would be game-breaking.  Most other historically specialized tips and shafts should be permitted; but they should not necessarily lend any combat modifiers except to cancel out the added difficulty for the absence of them.  Unless the DM has an elaborate homebrew that already reworks all combat mechanics (e.g., 2nd edition D&D's rules on armor vs. damage types), the specialized nonmagical arrows should be treated more as primarily for descriptive flavor and explicatory justification for a bonus that already is applied.  It may assist in the occasional license of furthering a basic task, but not much more.  Thus the unbarbed arrow would not grant a bonus against chainmail, even though this is why they existed in real life, but it could come in handy if the characters need to minimize damage to a rare beast they are trying to capture for spell components or taxidermy.  And it would be fine for the fletchings to glimmer in the son or shafts fluted and notched to add some crowd-pleasing whistling effect at a fair's archery competition.  And, since frog-crotch arrows were designed for cutting ropes and cords (e.g., in naval or siege warfare), the Mystatherian Archer should not be refused or given an prohibitive penalty to a DC 20 target shot when trying to sever the noose to rescue an ally.

CURVED SHOT/OPTIMAL ANGLE:

At 7th level you learn how to strategically align or curve shots so that errant ones maintain a high probability of successfully striking a nearby target instead.  When you make an attack roll with any arrow and miss, you automatically re-roll that attack against any target as long as it is either within ten feet on either side or within 30 feet directly behind the original target.

IMMOBILIZING MANEUVER:

At 10th level you can attempt to pin an adversary to the ground, wall, tree, or other suitable matter.  Your archer takes a -5 penalty to hit its target, which must make a Dexterity saving throw to resist being pinned by the arrow.  If this occurs the target receives the restrained condition that imparts a movement of 0, disadvantage on Dexterity saving throws, disadvantage on its attack rolls, and advantage for opposing attack rolls.  The restrained creature can use an action on its turn to try and break free with an Athletics check after each round, but otherwise the target is automatically freed after five rounds.

EAGLE-EYED FOCUS:

At 15th level you can choose to consolidate two of your attacks into one and use the extra time to aim a more effective shot with any remaining attacks that round or your first attack of the next round.

*  2 total attacks consolidated  =  +4 to Hit, +1d6/1d8 piercing damage (d6/d8 = bow type).
*  3 total attacks consolidated  =  +5 to Hit, +2d6/2d8 piercing damage (d6/d8 = bow type).
*  4 total attacks consolidated  =  +6 to Hit, +3d6/3d8 piercing damage (d6/d8 = bow type).

If your archer receives damage after choosing to consolidate attacks across multiple round, a Constitution saving throw is required to maintain concentration.  The difficulty is half the total damage taken, but with a minimum difficulty of 10 (e.g., 34 damage requires DC of 17, but a damage of 3, 5, or 9 requires a DC of 10).  If concentration is lost, the consolidated shots are lost too, but any remaining bonus attacks or reactions remain available.

PREEMPTIVE STRIKE:

At 15th level you have achieved mastery at awareness of developing threats and have honed your magical prowess to instinctively map out and fire a shot before anyone else.  Your archer gains advantage on surprise rolls in an encounter, and a +5 Initiative bonus.  Only the Initiative bonus will stack with the Alert feat, if applicable.

FEYWILD BANISHMENT:

At 18th level you use abjuration magic to try to temporarily banish your target for ten rounds to a harmless location in the Feywild.  The creature hit by the arrow must also succeed on a Charisma saving throw or be banished.  At the end of its next turn, the target reappears in the space it vacated or in the nearest unoccupied space if that space is occupied.