Annihilating Aura

You begin to exhude lashing shadowy tendrils of pure antilife energy to a distance of 20 feet. When a living creature starts its turn within this area, you may force it to succeed on a DC Constitution saving throw or take 17 (5d6) necrotic damage. Creatures in the area fail death saves automatically, instead of rolling, and cannot be stabilized without regaining at least 1 hit point.

At Higher Levels:
When you cast this spell using a spell slot of 5th level or higher, the damage increases by 2d6 for each slot above 4th.