Acid Fog

   You create a 20-foot radius sphere of fog centered on a point within range. The sphere spreads around corners, and the area within the sphere is heavily obscured. The fog is so thick and acidic it creates difficult terrain. Any creature that starts its turn inside the fog, or moves within the fog for the first time on a turn, takes 2d6 acid damage. The fog lasts for the duration, or until a powerful wind (at least 30 mph) disperses it.

At Higher Levels: When you cast this spell using a 4th level spell slot or higher, the radius of the sphere increases by 10 feet and the damage increases by 1d6 for each slot level above 3rd.