Death Blast

You target one creature within range. A bolt of dark energy surges toward that creature extending from you. The target must make a DC 16 Constitution saving throw. On a failed roll the creature takes 1d10 Necrotic damage for every number it missed the save by. On a successful save, that target takes 2d10 Necrotic damage. If the target is immune to Necrotic damage It takes 2d10 Radiant damage. If the target drops to 0 hp,  every creature within a 10 ft. radius that can see must make a DC 12 Constitution save or have Disadvantage on attack roll for their next turn.