Nine Lives Stealer Light Crossbow

Ammo: bolt [5.5e]

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.

Slow (Mastery): If you hit a creature with this weapon and deal damage to it, you can reduce its Speed by 10 feet until the start of your next turn. If the creature is hit more than once by weapons that have this property, the Speed reduction doesn't exceed 10 feet.

Ammunition: You can use a weapon that has the Ammunition property to make a ranged attack only if you have ammunition to fire from it. The type of ammunition required is specified with the weapon's range. Each attack expends one piece of ammunition. Drawing the ammunition is part of the attack (you need a free hand to load a one-handed weapon). After a fight, you can spend 1 minute to recover half the ammunition (round down) you used in the fight; the rest is lost.

Loading: You can fire only one piece of ammunition from a Loading weapon when you use an action, a Bonus Action, or a Reaction to fire it, regardless of the number of attacks you can normally make.

Two-Handed: A Two-Handed weapon requires two hands when you attack with it.

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