Circle of Decay

A sphere of toxic air ripples out in a 60-foot-radius. Each creature in that area must make a Constitution saving throw every time it ends it's turn in that area for the next two rounds They take 4d6 poison damage on a failed save, or half as much damage on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, the damage increases by 1d8 for each slot level above 6th.