Deathtouch

As you flourish your weapon, fist, or other body part, an aura or negative energy coalesces around it.  You brandish the weapon used in the spell’s casting and make a melee weapon attack with it against one creature within 15 feet of you (within the melee range of the weapon). On a hit, the target suffers the weapon attack’s normal damage plus necrotic damage equal to your spell casting ability modifier, and the creature can't regain hit points until the start of your next turn, during which time the aura clings to the target.

If you hit an undead target, it also has disadvantage on attack rolls against you until the end of your next turn.

This spell’s damage increases when you reach certain levels. At 5th level, the melee attack deals an extra 1d8 + your spellcasting ability modifier necrotic damage. The damage roll increases by 1d8 at 11th level (2d8) and 17th level (3d8).