Decaying Skull

You create a projectile that resembles a black skull that radiates necrotic and decaying energy. The projectile explodes in a 60 ft radius, all creatures within the radius must make a dexterity saving throw and take 72 (8d10) necrotic damage plus an additional 7 (3d4) decay damage on a failed save, and half as much on a successful one. The targets must also make an additional constitution saving throw or have the Decaying condition put on them for 1 minute. the targets can repeat this save at the start of each of their next turns.