Nine Lives Stealer Flail

You gain a +2 bonus to attack rolls and damage rolls made with this magic weapon.

Life Stealing: The weapon has 1d8 + 1 charges. When you attack a creature that has fewer than 100 Hit Points with this weapon and roll a 20 on the d20 for the attack roll, the creature must succeed on a DC 15 Constitution saving throw or be slain instantly as the sword tears its life force from its body. Constructs and Undead succeed on the save automatically. The weapon loses 1 charge if the creature is slain. When the weapon has no charges remaining, it loses this property.

Sap (Mastery): If you hit a creature with this weapon, that creature has Disadvantage on its next attack roll before the start of your next turn.

Proficiency: simple, flail Source: Dungeon Master's Guide (2024) p. 281