Hungersword

Weapon (greatsword), legendary (requires attunement)

This magic weapon is made of black adamantine with a bone hilt and pommel. You gain a +3 bonus to attack and damage rolls made with it. The sword has the following additional abilities.

• When you roll a 20 on the attack roll, the target takes an extra 10 necrotic damage and you heal 10 hit points. Neither of these effects happens if your target is a construct or undead.
• When you hit a celestial (or some other especially good mortal creature, such as a paladin or a devout cleric of a good deity), that creature takes an extra 2d10 necrotic damage.
• You can use the sword like a rod of absorption, but only to absorb good spells and spells from good spellcasters. There is no limit to how many spells the sword can absorb, but instead of converting stored energy into casting spells, as your bonus action you can use the absorbed spells to add +1 necrotic damage per level expended (maximum +10) to an attack with the sword.
• As your action you can use the magic of the sword to create a black, skull-shaped mark on the face, hand, or other prominent feature of any willing creature. You can’t use this property again until you finish a long rest. A creature with the mark is protected as if carrying a scarab of protection (with unlimited charges). The creature gains the ability to launch a pale gray ray of energy (a ranged spell attack). A creature struck by this ray must make a Dexterity saving throw. On a failed save, the target takes 10d6 + 40 necrotic damage. If this damage reduces the target to 0 hit points, it dies. On a successful save, the target gains two levels of exhaustion. Once the marked creature uses this ray, it loses the mark granted by the hungersword.

It is said that six of these swords exist.