Undying Decay

 You temporarily build the tips of your fingers up with necromantic energy before casting it upon a target creature. It will proceed to attack the flesh of the target, which makes their skin rapidly decay until only it’s skeleton remains. The target must make a Constitution saving throw. It takes 13d20 + 20 necrotic damage on a failed save, or half as much damage on a successful one.

A humanoid killed by this spell rises at the start of your next turn as a skeleton that is permanently under your command, following your verbal orders to the best of its ability.