This fabled and dreaded blade, once split apart to prevent it from causing a planar level destruction event, was previously wielded by a Demon lord, whos name has been lost to history. This demon lord was on the cusp of wiping from existence an entire plane, only to have been defeated by his own progeny, with the help of a cluster of young dragons. The sword was split into 2 pieces. one was cleansed and was kept under lock and key by the descendants of the demons progeny, the other was sealed in a supposedly unreachable location deep in the abyss, never to be seen again. Now reformed, its mere existence is a call to the dark forces of the multiverse, spelling doom for all unless the blade can be destroyed again. The sword is said to be able to cut through anything, even the very fabric of space and time.

This sword gains a +3 bonus to attack and damage rolls made with it and deals an additional 6d8 Force damage with each attack, or 6d10 force damage instead if wielded with both hands. Additionally this sword gains the finesse property.  You gain a +40 to your movement speed.  You DEX is set to 30 while attuned to this blade. 

Dark Slayer: While attuned, attacks made with this sword become a critical hit on a roll of 18-20 on the D20 as well as gaining a +5 bonus to all attack/damage rolls made with this weapon. When it lands a critical hit, it deals an additional 6 damage die of force damage as part of the attack. Critical hits with this weapon leave lingering injuries and limbs or other body parts removed by it are instantly destroyed. Additionally you may teleport up to 120 feet as a bonus action and make two attacks as part of your bonus action.  A number of times equal to your proficiency modifier, you may perform a version of Severance that deals 6d10 force damage, and knocks a target of gargantuan size or lower prone.

Eclipse:  You move this blade in a circular motion, leaving an energy trail behind it, once the trail is complete, a column of negative energy rains onto the area from above. All creatures in a 300 Ft wide column centered around yourself must make a DC 27 Constitution Saving throw, Undead Creatures gain advantage on this save. On a failed save, a creature takes 210(20d20 Necrotic) and 210(20d20 Force Damage) and has its Strength reduced to 1 for 1 minute or until a Greater Restoration or healing spell of at least 6th Level is cast on it. On a successful save, a creature takes 1/2 damage and its strength is not reduced.

Judgement Cut: You become so fast with this sword that you can make attacks with it and sheathe it faster than an eye can blink. When you are targeted by an attack roll, you may use your reaction to increase your AC by an amount equal to your dexterity bonus against that attack. If this would cause the attack roll to miss, you may immediately follow up as part of the same reaction and take the attack action. If you have multiple attacks you make all of them that you normally would when taking the attack action.  A number of times equal to your proficiency modifier, you may perform the spell *Severance.

Bend of the Weave:  You may cast any spell at 9th level followed by any spell of 6th level or lower.  You gain access to all of Ebanus's knowledge of spell weaving and swordsmanship.  

 Summoned Swords: While attuned, you may summon several ethereal blue swords that surround you and grant you various bonuses. When you use this bonus action you summon a number of these floating ethereal swords equal to your proficiency bonus. The swords hover and spin around you and remain for 1 minute or until you use this ability again. You may use this ability a number of times equal to half your proficiency bonus, regaining all expended uses upon completing a long rest. While the swords are summoned you gain the following bonuses;

• Your AC increases by an amount equal to the number of swords you currently have around you.
• As a bonus action you may make a ranged spell attack with the swords, sending them flying at a target within 60 feet of you. You may send any number of the swords surrounding you as part of this attack. Charisma is your spellcasting modifier for this and on a hit, the swords deal 10d8 Force damage. Regardless of whether or not the swords hit a target, any sword used for this attack is destroyed.
• When another creature hits you with a melee attack within 10 feet of you, they take slashing damage equal to twice the number of swords around you and one of your swords is destroyed.
• When you are subjected to an effect that forces you to make a Dexterity Saving throw, you may sacrifice all the swords you currently have as a reaction, gaining a bonus to the roll equal to the number of swords lost this way. If you succeed the saving throw, you take no damage.

Form of Sin: While attuned, as an action, you may Transform yourself into a demonic form. You stay in this form for 10 minutes or until you reach 0hp. While in this form you gain the following benefits;

• You gain 1000 Temp Hp, if any of these remain when the transformation ends, they are lost.
• You gain immunity to Necrotic, Fire, and Lightning damage.
• Melee attack rolls you make are made at advantage and deal an additional 12d12 Fire Damage, this Damage ignores resistance and immunity.
• You gain a fly speed equal to triple your movement speed.
• You gain proficiency in Strength and Constitution Saving Throws.
• You fall under the effects of Foresight and Haste.
• You gain 3 legendary resistances.

World Splitter: While attuned, you may cast the Gate spell a number of times equal to half your proficiency modifier from the sword, without expending a spell slot or material components. After expending these charges, you must complete a long rest before doing so again.  Once per long rest, you may perform World Splitter Judgement Cut which targets all enemies within a mile radius.  Massive amounts of Tainted Energy pouts out of you in large red arcs followed by red/black lighting pouring from your sheath as you take your stance, slowly drawing Yamato from your perspective, but faster than the eye can perceive.  The result of this attack is that everything within line of sight takes 1500 slashing/force damage from this variant Judgement Cut.  Structures of your choice within this radius are also destroyed from the uncountable slashes.  Those that witness this attack and survive or see it from a distance only see the calm before the storm before reality around the area shatters and breaks from the actual slashes.

Approaching Storm: While attuned to this weapon, the following spells are added to your list of spells known. You may cast each of these spells once without expending a spell slot or material components once, after which you must complete a long rest before doing so again; Blink, Shadow of Moil, Severance*, Simulacrum, Final Judgement*.

Random Properties:

• 3 Minor Beneficial Properties: You know the Dark Blade* Cantrip and may cast it at will; While attuned to the artifact, you can use an action to cast Zephyr Strike from it. After you cast the spell you can’t cast it again until the next dawn; While attuned to the artifact, you gain a +1 bonus to Armor Class.
• 2 Major Beneficial Properties: While attuned to the artifact, your Dexterity score increases by 2, to a maximum of 24; While attuned to this artifact you cant be blinded, deafened, petrified, or stunned.
• 3 Minor Detrimental Properties: While you are attuned to the artifact, holy water within 10 feet of you instantly fades out of existence from the massive amounts of Tainted Energy; While you are attuned to the artifact, your flaw is amplified in a way determined by the DM;  While attuned to this artifact, you emit a very dangerous aura that most living and even unliving entities can feel, making them incredibly weary of you.  Like a heavy rain bearing down on them, your spiritual pressure skyrockets and explodes when using this blade and its devastating abilities.
• 2 Major Detrimental Properties: When you attune to this artifact, there is a 10 percent chance that a deity will send an avatar or champion out to attempt to destroy or capture this artifact.  (Empyrean)  ; When you become attuned to the artifact, you take 8d10 psychic damage from the memories and sorrow of Ebanus.

After defeating the BBEG Ebanus, Oni Lord of Sorrow and Betrayal after he ascended to godhood his blade was left behind.  This blade, unbeknown to the wielder, contains an echo of Ebanus himself which slowly afflicts the wielder over time with the spark of betrayal and sorrow.  Ebanus's echo leaves the wielder feeling sorrowful, angry, even betrayed by those around them.  Inevitably, this echo breaks the wielder down far enough to the point were possession becomes possible allowing the echo to actually communicate with the wielder and further break them down to become their "friend" and mentor, allowing more control and influence to spread. 

While attuned to this blade, you become cursed  where you do not want to be parted with this blade.  If anyone tries to take this blade from you, you become enraged and even willing to kill the one/ones whom would try to take this "wonderfully powerful" blade away from you.  A prize you won fair and square to achieve your goals. 

*Spells marked with an asterisk are homebrew spells that can be found here on DnDBeyond.

Proficiency with a Longsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: slayer of Ebanus, the Black Prince, Oni Lord of Sorrow and Strife, Versatile, Sap