Edict of Doom

You issue a baneful edict, invoking doom upon a creature you can see within range. An incorporeal black mark appears above the creature’s head and hovers there for the spell's duration. Whenever the spell's target makes an attack roll, ability check or saving throw for the duration, you can activate the black mark to change the target's roll to a 1. When you do so, the mark disappears and the target must make a Constitution saving throw. On a failed save, it takes 4d6 necrotic damage. Once the mark has disappeared, the spell ends.