Forged in the stars on the Abyssinian Throneworld

 

The blade of the greatsword is forged from the metals of a thousand conquered worlds in the fires of a dying star. Demonic magicks provide a +3 bonus. 

In combat, on a Natural 20 or if the target is reduced to 0 hp, they must make a DC 19 Charisma Saving Throw or have their soul entrapped within the greatsword. Nothing short of a Wish may release the soul. What is left of their body evaporates as ethereal smoke and any magical items becomes lost in the Astral plane.

Heavy Metal.The greatsword is unusually heavy. Any wielder with less than 14 Strength suffers a DISADVANTAGE in attacks.

Ancestral Feud. The greatsword is has a nascent sentience that creates urges in the wielder to destroy all rakshasa, leonin, tabaxi, and other feline creatures. The wielder must make a DC 8 Wisdom Saving Throw to not attack tabaxi and feline creatures on sight. On a successful save, they do not have to check again against that target until after a long rest.

Summon Demon (1/day). Once per day, the wielder may carve a portal in space to summon a demon Summon Greater Demon as a 9th level spell. The optional component of the summons involves tracing the circle on the ground with the blade of the greatsword which provides protection as per spell description. Demons may still be summoned without that component.

Cost of Attunement. Any non-fiend or non-tiefling that attunes to this artifact suffers 1d6 necrotic damage at the beginning of the day. They cannot heal from rest or other non-magical treatments.  

 

The Price of Death

Should the wielder die, they too must make a DC 19 Charisma Saving Throw or have their soul entrapped and their magical belongings lost to the Astral plane.

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

Notes: Bonus: Melee Weapon Attacks, Fighter, Tiefling, fiend, Banishment, Combat, Cursed, Heavy, Two-Handed, Graze