Ebon Ray of Doom

You fire a ray of black energy that reduces the rate at which a target can recover hit points. Make a spell attack roll. On a successful hit, the target takes 2d8 necrotic damage. The target must make a Constitution save against your spell DC. On a failed save, any healing benefit on the target is halved for the duration of the spell. At the end of each of the target's turns, it may repeat the saving throw. On a success, the spell effect ends early.

At higher levels, the damage increases by 1d8 for every level above 4th.