An unknown black substance crawls out from the ground and devours everything in its path. Each creature in a 10-foot-radius sphere at the point you choose must make a Dexterity saving throw or be drained by the substance, taking 3d8 necrotic damage. On a successful save, the creature takes half as much damage.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 1d8 for each slot level above 2nd.