Darkness Burst

A dark bullet zooms from your pointing finger to a point within range and then explodes with a whooshing noise into an explosion of darkness. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 7d6 necrotic damage on a failed save, or half as much damage (round down) on a successful one. 

The darkness spreads around corners.

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