With a wave of your hand, you imbue a creature with hellish energy at the moment it dies. Using your reaction when a creature dies within range, you cause its corpse to explode in a ball of fire. Each creature in a 15-foot sphere centered on the corpse must make a Dexterity saving throw. A creature takes 2d8 damage on a failed save, or half as much damage on a successful one. 

At Higher Levels: When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 1d8 for each slot level above 2nd.