Three Phases. The Beholder Knight will reach phase 2 at half of its health. Upon hitting 0 hp, the Beholder Knight enters phase 3, fully restoring all hp. The phase transitions go as follows: when reaching phase 2 they take the eye of death from their sword and consume it. When reaching phase 3 they eat the eye of Disintegration  and take out their own eyes and putting them into their 2 eye-less swords, turning them into swords death

Quick Stow. The Beholder Knight chooses what 2 swords to use for its turn at the beginning of every turn, for free.

Spellcasting. The Beholder Knight is a 5th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 12, +5 to hit with spell attacks). The Beholder Knight has following Wizard spells prepared:
1st level (10 slots): [catapult]

2nd level (7 slots): [levitate]

5th level (5 slots): [telekinesis]

Phase 3.

Swords Of Death. The Beholder Knight's 2 swords of Death act as their own enemies, with seperate initiative. They have an AC of 0, count as small, and have 24 (2d20) hp. They can only be damage if a creature within 5ft makes a strength roll. Their roll determines how much damage the sword takes. If the sword is reduced to 0 hp, the creature wields it as a weapon. The swords can only do 2 things in a turn: move 30ft and plunge into the ground. The turn after they plunge into the ground, a 10ft radius aoe activates. Any creatures in this aoe have to immediately roll Death saving throws. The swords count as small constructs.

Spellcasting. The Beholder Knight is a 1st-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 12, +5 to hit with spell attacks). The Beholder Knight has following Cleric spells prepared:

1st level (7 slots): [Command]

Final Stand. When the Beholder Knight is reduced to 0 HP, it will take its two swords of death and begin violently stabbing the ground. 12 (5d4) skeletons are spawned and the players are given 5 turns to kill all the skeletons. On a failure, the Beholder Knight stabs both blades into the ground, causing an arena-wide aoe, reducing all players' HP to 0

Phase 1

Blade Of Charming The Beholder Knight strikes with a blade imbued with a beholder's eye of charming.  Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 6 (1d4 + 3) slashing damage. The targeted creature must succeed on a DC 11 Wisdom saving throw or be charmed by the Beholder Knight for 4 turns, or until the creature is harmed.

Blade Of Paralyzation The Beholder Knight strikes with a blade imbued with a beholder's paralyzing eye. Melee Weapon Attack: +3 to hit, reach 5 ft., 3 target. (Jump between enemies within 5 ft of eachother) Hit: 6 (1d4 + 3) thunder damage. The targeted creature must succeed on a DC 15 Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Frightening Blade The Beholder Knight strikes with a blade imbued with a beholder's eye of fear. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 6 (1d4 + 3) slashing damage. The targeted creature must succeed on a DC 15 Wisdom saving throw or be frightened for 5 turns. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Blade Of Slowing The Beholder Knight strikes with a blade imbued with a beholder's eye of slowness. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 6 (1d4 + 3) slashing damage. The targeted creature must succeed on a DC 16 Dexterity saving throw. On a failed save, the target's speed is halved for 1 minute. In addition, the creature can't take reactions, and it can take either an action or a bonus action on its turn, not both. The creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Blade Of Enervation The Beholder Knight strikes with a blade imbued with a beholder's eye of enervation. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 3 (1d4) necrotic damage. The targeted creature must make a DC 13 Constitution saving throw, taking 5 (2d4) necrotic damage on a failed save, or half as much damage on a successful one.

 Blade Of Telekinesis The Beholder Knight strikes with a blade imbued with a beholder's eye of telekinesis. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 6 (1d4 + 3) slashing damage. If the target is a creature, it must succeed on a DC 14 Strength saving throw or the Beholder Knight may move the creature up to 30 feet in any direction. It is restrained by the blade's telekinetic grip until the start of the beholder's next turn, until the Beholder Knight drops or stows the telekinetic blade, or until the Beholder Knight is incapacitated.

If the target is an object weighing 300 pounds or less that isn't being worn or carried, it is moved up to 30 feet in any direction. The Beholder Knight can also exert fine control on objects with this ray, such as manipulating a simple tool or opening a door or a container.

Blade Of Sleep. The Beholder Knight strikes with a blade imbued with a beholder's eye of sleep. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 6 (1d4 + 3) slashing damage. The targeted creature must succeed on a DC 13 Wisdom saving throw or fall asleep and remain unconscious for 1 minute. The target awakens if it takes damage or another creature takes an action or bonus action to wake it. This has no effect on constructs and undead.

Blade Of Petrification. The Beholder Knight strikes with a blade imbued with a beholder's eye of petrification. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 6 (1d4 + 3) slashing damage. The targeted creature must make a DC 14 Dexterity saving throw. On a failed save, the creature begins to turn to stone and is restrained. It may repeat the saving throw at the end of each turn. On a success, the effect ends

Blade Of Disintegration. The Beholder Knight strikes with a blade imbued with a beholder's eye of petrification. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 3 (1d4) If the target is a creature, it must succeed on a DC 11 Dexterity saving throw or take 1 force damage. If this damage reduces the creature to 0 hit points, its body becomes a pile of fine gray dust.

Blade Of Death. The Beholder Knight plunges a blade imbued with a beholder's eye of death into the ground, ending it's turn. The next turn, the Beholder Knight loses it's bonus action and movement, but causes a 30ft radius aoe. Any creature in this aoe, excluding the Beholder Knight will be forced to roll all death saving throws, all in a single turn. Only 2 successful rolls are necessary to succeed.

Ring of Blades. The Beholder Knight creates a ring of 4 to 10 blades around itself with a radius up to 60ft. The blade's continue moving until hitting a wall or creature. RangedWeapon Attack: +7 to hit. Hit: 6 (2d4+1) piercing damage

Phase 2

Beholder's Blades. Any of phase 1's first 9 actions may be used

Flying Strike. fly up and strike down a creature, applying the effect of the sword used (see Beholder's Blades action). The creature moves as far as his attack reaches.Melee Weapon Attack: +4 to hit, reach 15 ft., Hit: 6 (1d8+1) piercing damage. The attack can target multiple creatures if they are all in a straight line, within 15 ft. Any creature hit by this attack and 15ft from the creature's starting position takes an extra 1d4 damage and is knocked prone as the blade stabs them into the ground 

Necrotic darts. Shoots 3 darts utilising death, shot from the 15ft in front of the Beholder Knight. RangedWeapon Attack: +2 to hit, range 0/30 ft., 3 target. On a hit, if the target is harmed in the next 3 turns, their hp is reduced to 1, unless the target is within 5ft of the Beholder Knight, or up against a wall, where the dart will explode upon collision. The darts can shoot through multiple target's.

Blade Rain. The Beholder Knight charges an aoe for 1 turn. Beginning this action ends its turn, and he second part truggers on the beginning of its mext turn, in which 10 swords fall and rise, raining down in a 30ft radius around the boss. Being caught in the sword rain causes the creature to be automatically hit. Hit: 3 (1d4) piercing damage, and a 1d10 is rolled for each creature hit (reroll duplicates) to determine the effect (see the first 9 actions in phase 1 for first 1-9 on d10 roll) and a 10 causes the Beholder Knight to be given one more bonus action.

Leap Of Death. The Beholder Knight leaps into the air, ending its turn and telegraphing where it will land, which may be anywhere in the arena. At the end of the next player character's action, bonus action, movement or free action etc. The Beholder Knight will slam down, with a 10ft aoe, forcing any creatures caught in the aoe to suffer the effects of the Necrotic Darts action.

Bite. Melee Weapon Attack +4 to hit , reach 5 ft., one creature. Hit 4 (1d4 + 2) piercing damage

 Clawed Slash. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit 5 (1d6 + 2) slashing damage.

Multiattack.  The Beholder Knight makes 2 attacks, each may be either a bite or a slash

Empty Blade. The sword, now having lost its eye of death is naught but a regular sword. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 6 (1d4 + 3) slashing damage

Phase 3

The Beholder Knight keeps any actions from phase 2 except for empty Blade, leap Of Death, and necrotic darts.

Field of Enchantment. The Beholder Knight plunges the blade of charming into the ground. Any creatures in a 5ft radius are under the spell 'Command'

Blade Of Charming. The Beholder Knight strikes with a blade imbued with a beholder's eye of charming. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 6 (1d4 + 3) slashing damage. The targeted creature must succeed on a DC 11 Wisdom saving throw or be charmed by the Beholder Knight for 4 turns, or until the creature is harmed.

 Blade Of Thunder. The Beholder Knight lifts his blade of Paralyzation into the air, calling upon thunder, channeling into his blade, before striking down his enemies. RangedWeapon Attack: +1 to hit, range 0/40 ft., 3 target. Hit: 12 (2d8+3). If hit, The targeted creature must succeed on a DC 15 Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. This effect applies to any creature within 5ft of the targeted creature.

Thunderous Leap. The Beholder Knight leaps into the air, ending its turn and telegraphing where it will land, which may be anywhere in the arena. At the end of the next player character's action, bonus action, movement or free action etc. The Beholder Knight will slam down, with a 10ft radius aoe,  forcing any creature in the aoe succeed on a DC 15 Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Nightmare Blade. The Beholder Knight strikes with the blade imbued by the eye of fear. Melee Weapon Attack: +10 to hit, reach 10 ft., 1 target. Hit: 4 (1d4 + 1) slashing damage. Any creature hit by this attack must succeed on a DC 14 Wisdom (insight) saving throw or be transported to a realm created from their own fear. They are trapped within this realm until they kill all creatures within. The creatures within are of the DM's choice, although they usually relate to the creature's fears or backstory, taking them back to the worst moments in their life. Each enemy killed within this realm deals 1d4 damage to the Beholder Knight and prevents removes one legendary action. If the Beholder Knight has telegraphed a charged up attack but not performed the attack yet, killing a creature in this realm can Stun the Beholder Knight out of the attack. Within this realm no one outside can interact with or be interacted with by the creature inside.

Blade of Greater Telekinesis. The Beholder Knight strikes with a blade imbued with a beholder's eye of telekinesis. Melee Weapon Attack: +3 to hit, reach 5 ft., 5 target. Hit: 8 (1d10+ 3) slashing damage. If the target is a creature, it must succeed on a DC 17 Strength saving throw or the Beholder Knight may move the creature up to 100 feet in any direction. It is restrained by the blade's telekinetic grip until the start of the Beholder Knight's next turn, or until the Beholder Knight drops or stows the telekinetic blade, or until the Beholder Knight is incapacitated. Whilst the creature is restrained, the Beholder Knight has fine control over the creature and any items on its person, allowing it to move limbs, contort the body and loosen the creature's grips on weapons.

If the target is an object weighing 1000 pounds or less that isn't being worn or carried, it is moved up to 30 feet in any direction. The Beholder Knight can also exert fine control on objects with this ray, such as manipulating a simple tool or opening a door or a container.

Blade Of Dreams. The Beholder Knight strikes with a blade imbued with a beholder's eye of sleep. Melee Weapon Attack: +7 to hit, reach 10 ft., 1 target. Hit: 8 (1d10+ 3) slashing damage. The targeted creature must succeed on a DC 13 Wisdom saving throw or fall asleep and remain unconscious for 1 minute. The Beholder Knight has control of the target's dreams whilst asleep. The creature can only be waken by succeeding on a DC 13 Wisdom check every turn to wake, or another creature using a full turn to wake them. Upon waking, the creature's speed is halved as they experience a drowsy state of sleepiness and any Dexterity, strength, charisma, intelligence or wisdom based saving throws take a -2 debuff for 2 turns.

Blade Of Petrification. The Beholder Knight strikes with a blade imbued with a beholder's eye of petrification. Melee Weapon Attack: +5 to hit, reach 5 ft., 1 target. Hit: 8 (1d10 + 3) slashing damage. The targeted creature must make a DC 14 Dexterity saving throw. On a failed save, the creature begins to turn to stone and is restrained. It may repeat the saving throw at the end of each turn. On a success, the effect ends. Whilst the creature is turned to stone, they are replaced by a stone golem with unlimited hp, halved damage and no multiattack. When the effect ends, the creature turned to stone appears at whatever location the stone golem is in.

Ring of Blades. The Beholder Knight creates a ring of 4 to 10 blades around itself with a radius up to 60ft. The blade's continue moving until hitting a wall or creature. RangedWeapon Attack: +7 to hit. Hit: 6 (2d4+1) piercing damage

Flying Death Strike. fly up and strike down a creature with the swords of death. The creature moves as far as his attack reaches.Melee Weapon Attack: +1 to hit, reach 15 ft., Hit: 8 (1d10+3) piercing damage. The attack can target multiple creatures if they are all in a straight line, within 15 ft. Any creature hit by this attack and 15ft from the creature's starting position takes an extra 1d4 damage and is knocked prone as the blade stabs them into the ground. Any creature hit by this attack also is forced to do all saving throws at once, until they succeed or fail. When recalling the blades at the beginning of this action, any players wielding the blades must make a DC 10 strength check. On a success, they lose the blade's. On a failure, they lose the blade's and take 5 (1d10) bludgeoning damage

Death Vortex. The Beholder Knight recalls his death blades. When recalling the blade's at the beginning of this action, any players wielding the blades must make a DC 10 strength check. On a success, they lose the blade's. On a failure, they lose the blade's and take 5 (1d10) bludgeoning damage. The Beholder Knight then spins with the swords, projecting a dark magic out from the tips of their blades. Melee Weapon Attack: +3 to hit, reach 60 ft circle., Upon a hit, the target's must make a DC 10 Constitution check or have their HP reduced to 0, and make all saving throws at once. Only 2 successes are necessary to survive. This action may only be used once per encounter.

Phase 1

Beholder's Blades. Can attack with the Beholder blade attacks used as phase 1 actions (blade of charming, blade of paralysation, frightening Blade, blade of Slowing, blade of enervation, blade of telelekinesis, blade of sleep, blade of petrification and blade of disintegration)

Spellcasting. If the Beholder Knight is holding the telekinesis blade, it may use spellcasting.

Phase 2

Cocoon Of Feathers. The 2 wings envelop the Beholder Knight in a cocoon like shape. Each player in a 60ft radius must make a DC 13 Constitution check. On a failure, they take 1d4 damage. On a success, the damage is halved. Any damage dealt is given to the boss as hp healed.

The Beholder Knight has access to any bonus actions from phase 1

Phase 3

Paralyzing Parry. The targeted creature must succeed on a DC 7 Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Half-Sworded Parry. if an enemy creature makes an attack with a melee Weapon, they must succeed on a DC 23 - weapon range strength check. On a success, the attack succeeds. On a failure, the attack fails and the Beholder Knight makes a counter attack that automatically hits, dealing 1d6+1 slashing damage.

Dust Toss. The Beholder Knight creates ash, throwing it in the eyes of any creature making an attack. The target loses their attack bonus when making their attack roll.

Blade Whip (Costs 1 Action). Through telekinesis 9 swords are projected forwards, moving In a whip like formation. This attack hits creatures in a 40ft line in front of the Beholder Knight. Melee Weapon Attack: +1 to hit, reach 40 ft., 9 targets Hit: 6 (1d4 + 3) slashing damage. Another legendary action (one of 2 options) can be used to perform a follow up at the beginning of the Beholder Knight's next turn:

     Blade Whip Follow-Up (Costs 1 Action). The Beholder Knight makes a horizontal swipe with the chain of blades. MeleeWeapon Attack: always hits, reach 30ft cone., Hit: 8(1d10+3) 

     Blade Ring (Costs 1 Action). The Beholder Knight spins around with the chain of blades. Melee Weapon Attack: always hits, reach 15ft circle., Hit: 8 (1d10 + 3) 

Blade Whip Swipe (Costs 1 Action). Through telekinesis 9 swords are projected forwards, moving In a whip like formation and make a horizontal swipe. MeleeWeapon Attack: +1 to hit, reach 30ft cone., Hit: 5(1d4+3) 

Blade Ring (Costs 2 actions). Through telekinesis 9 swords are projected forwards, moving In a whip like formation, as the Beholder Knight spins wildly. Melee Weapon Attack: +5 to hit, reach 15ft circle., Hit: 8 (1d10 + 3) 

 Phase 2 

Spinning Blade (Costs 2 actions). The Beholder Knight throws 3 spinning swords. RangedWeapon Attack: +3 to hit, range 10/40 ft., 3 target. If hit, the target must roll a 1d10, corresponding to the effects of the beholder's blades. a 10 results in the empty Blade being thrown, which increases damage by 1d4 slashing damage

Any phase 1 legendary actions are still available in phase 2

Phase 3

Any phase 1 or 2 legendary actions are still available In phase 3 (for spinning Blade, change 1d10 to 1d8, removing empty Blade and Blade of disintegration.)

Ashen Hands. The Beholder Knight lifts their hands into the air. On their next turn they plunge their hands into the ground, causing 13 (1d10+8) force damage to any creature in a 15ft wide and 20ft long square ahead of the Beholder Knight. Any creature reduced to 0 hp by this attack is reduced to a pile of dust. The floor affected by this attack's aoe is also reduced to ash, creating a hole in the arena 

Lightning Stakes. The Beholder Knight flies into the air, lifting their sword of thunder up, and allowing it to float, as their hands move to the side, 2 stakes of lightning strike, caught in their hands. On their next turn, they swoop down, making a cross cut with the stakes of lightning. By doing so, they move up to 20ft, and automatically hit any creature within 60ft, in the direction they are looking, dealing 2d6+3 (10) thunder damage. On the next player turn, the sword of thunder flies down, attacking anyone who was hit by the lightning stakes. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 6 (1d4 + 3) slashing damage. Anyone hit by either the lightning stakes or the thunder sword suffers the paralysation effect seen in the Blade of Thunder Action.

Blades Of Death. The Beholder Knight plunges a blade imbued with a beholder's eye of death into the ground. The next turn, the Beholder Knight loses it's bonus action and movement, but causes a 30ft radius aoe. Any creature in this aoe, excluding the Beholder Knight will be forced to roll all death saving throws, all in a single turn. When recalling the blade's at the beginning of this legendary action, any players wielding the blades must make a DC 10 strength check. On a success, they lose the blade's. On a failure, they lose the blade's and take 5 (1d10) bludgeoning damage

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Mythic Action Name (Costs # Actions). Enter the description for your mythic action.