Life Drinker

With a baleful word and a vicious strike you draw the very lifeforce from your target. Make a melee weapon attack roll . A creature damaged by this attack makes a Constitution saving throw , and on a failure you gain hit points equal to one of its hit dice + your Constitution modifier (two on a critical hit). as if you had taken a short rest . This does not deal additional damage, but does expend the hit die if the creature is capable of spending them.