Barrier of Death

You draw a circle in diamond dust on the ground and recite the incantation, releasing negative energy into the form of a 30-foot radius bubble centered on you. You, any targets you choose, and creatures made of negative energy are unaffected by this spell. All unprotected creatures within or who enter the bubble must make a Constitution saving throw. It takes 12d8 + 50 necrotic damage on a failed save, half as much on a successful one.

A creature who dies as a result of this spell raises up next turn as an undead form of itself permanently under your control, unquestioningly obeying your commands to the best of its ability.