Annihilation

Shadows wreathe one creature you can see within range. The target must make a Constitution saving throw. It takes 6d8 necrotic damage on a failed save, or half as much damage on a successful one. On a failed save, the target also begins being consumed by the darkness. At the end of each of its turns, the target repeats the saving throw. It takes 4d8 necrotic damage on a failed save, and the spell ends on a successful one. This magical darkness can't be illuminated by and dispels nonmagical light or one created by a spell of 5th level or lower.

If damage from this spell kills a target, the target leaves no remains.