Epitaph

Weapon (greatsword), legendary (requires attunement)

A massive, graven blade resembling a stone memorial. You gain a +3 bonus to attack and damage rolls made with this magic weapon, which deals an extra 2d8 necrotic damage to Undead creatures that ignores resistances and immunities. 

Entomb. As an 8-hour ritual you can bind the essence of a large or smaller humanoid creature that died within the last hour by placing its body upon the blade of this weapon alongside diamonds worth 1000 gold pieces, both of which are consumed upon completion. After the ritual, the skeleton of the creature appears on the surface of this blade. 

While a creature is bound to this weapon, it cannot be resurrected by any means. If you use this property while a creature is already bound to this weapon, the previously bound creature's essence is destroyed and replaced with the new body and soul. 

Awaken. As an action, you can reanimate the creature that was bound by the Entomb property. The creature appears in an unoccupied space within 5 feet of you as its corporeal body reforms around its skeleton. The creature appears with its maximum hit points, spell slots, and uses of its abilities it had in life, unless any would be subject to removal (DM's discretion, ex. a Paladin's Oath spells). 

The creature is considered undead, cannot speak, is immune to being charmed and frightened, appears with the same equipment and items it had when bound to this weapon (except magic items), and has the same features and actions as it did in life. It takes its turn after yours and follows your verbal commands, which it does its best to obey.  You can specify a simple and general course of action, such as "Attack that creature," "Run over there," or "Fetch that object." If the creature completes the order and doesn't receive further direction from you, it defends and preserves itself to the best of its ability. After 1 hour, the creature's body dissipates and the skeleton reforms upon the surface of this weapon as long as you two are on the same plane of existence. 

The creature cannot regain hit points by any means, and if it is reduced to 0 hit points its body turns to dust and its essence is no longer bound to this weapon. Once you use this property it can't be used again until you finish a long rest. 

Barter. If a creature is bound to this weapon by the Entomb property, when you are reduced to 0 hit points you can choose to destroy the bound creature's essence. If the creature has been reanimated by the Awaken property when you do so, it immediately turns to dust and its essence is destroyed. You drop to 1 hit point instead. If you use this property, the creature whose essence was destroyed cannot be brought back to life by any means except by the Wish spell. 

Curse: Death Toll. This weapon is cursed. Once you use the Barter property, it extends the curse to you. While cursed in this way, if you die your body turns to dust and your essence is bound to this weapon as though by the Entomb property. Your skeleton appears on the surface of this blade. 

Death, such a wasteful thing. So many pass with so much left to be done, lives empty and incomplete; a fate most cruel. 

Is it not better to live on for the sake of others? To assist in their endeavors, even after expiration, making the world a better place. Truly, there can be no greater sacrifice or purpose in one's existence than this; eternal, unending, everlasting, undying, infinite, timeless servitude. Now...serve.

Swordtember Prompt: Necromancer