Corpse Explosion

The user detonates a corpse within range. Each creature in a 10 foot radius sphere centered on the target must make a Dexterity saving throw. Target(s) take 3d6 necrotic damage on a failed save, or half as much damage on a successful one. Corpses that are detonated are unable to be reanimated. 

When a zombie or skeleton under your control dies, you can immediately cast this spell targeting it. When cast in this way, the casting time is reduced to 1 reaction.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d6 for each slot level above 1st.