Defiling Fireball

A sickening green streak flashes from your pointing finger to a point you choose within range and then blossoms with a low roar into an explosion of wicked green flame. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 4d6 fire damage and 4d6 necrotic damage on a failed save, or half as much damage on a successful one. You heal equal to the total amount of necrotic damage dealt.

The fire spreads around corners. It rots any non-magical objects able to rot in the area that aren't being worn or carried.

At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the damage increases by 1d6 of each damage type for each slot level above 5th.