Punishing Strike

Necromancy Cantrip
Casting Time: 1 action
Range: Self (5 Feet)
Components: V, S
Duration: 1 round
As part of the action used to cast this spell, you must make an unarmed strike or melee weapon attack against one creature within the spell's range, otherwise the spell fails. On a hit, the target suffers the attack's normal effects. In addition, a black web of necrotic energy radiates across its skin from where it was struck until the start of your next turn. If the target willingly takes a reaction before then, it immediately takes 1d8 necrotic damage, and the spell ends.
This spell's damage increases when you reach higher levels. At 5th level, the melee attack deals an extra 1d8 necrotic damage to the target, and the damage the target suffers for taking a reaction increases to 2d8. Both damage rolls increase by 1d8 at 11th level and 17th level.
Classes: Warlock, Sorcerer Wizard