Blasphemy

Adapated from Genuine Fantasy Press

Level 3 Necromancy

(Bard)
Casting Time: Action
Range: Self (60-foot emanation)
Components: V
Duration: Concentration, up to 1 minute
An aura radiates from you in a 60-foot Emanation for the duration, which curses and wills away healing magics. Each time a creature in the aura regains Hit Points from magic (such as a spell or taking the Magic action, but not drinking a potion), it must succeed on a Charisma saving throw or lose the Hit Points it just regained and take 1d6 Psychic damage.
Using a Higher-Level Spell Slot. The damage increases by 1d6 for each Spell Slot level above 3.