Charnel Touch

Necromantic energy flows through your body, concentrating in your hands, harming a living creature you try to touch, or healing and undead creature. Make a melee spell attack against the target. On a hit, a living target takes 1d8 Necrotic damage, and it can't gain hit points until the start of your next turn, while an undead target is healed for half that amount (minimum one). 

The spell's damage increases by 1d8 when you reach 5th level (2d8), 11th level (3d8), and 17th level (4d8).