Corpse Explosion

This spell creates an explosive undead servant. The spell causes a reanimated dead to emerge from the ground and move up to 15 feet from the caster. The undead can be a skeleton or a zombie (the GM has the creature's game statistics). The undead will remain idle on the ground after it has moved.

On each of your turns for the duration of the spell, you can use a bonus action to mentally command the undead to explode making all creatures within a 15 feet radius make a DEX saving throw. On a fail, the creature takes 4d6 Necrotic damage. On a success, the creature takes half as much damage. If you issue no commands, the creature remains idle. The undead retreats back beneath the ground if it takes 20 damage or more.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, you deal an extra 1d6 necrotic damage for each slot level above 2nd