Blackflame Circle

A circle of black candles, each with a dark flame, encircles the target area,  a vortex of choking shadow swirling about inside. Each creature in a 20-foot-radius sphere centered on that point must make a Constitution saving throw. A target takes 6d6 necrotic damage on a failed save, or half as much damage on a successful one. 

Targets who fail their saving thrown are also Blinded until the end of their next turn

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.