Acid Fog

You create a 20-foot-radius sphere of fog centered on a point within range. The sphere spreads around corners, and its area is heavily obscured. The area inside the fog is thick and cloying, and acts as difficult terrain. The fog is also highly acidic. A creature that ends its turn inside the fog takes 4d10 acid damage. A moderate wind (at least 10 miles per hour) disperses the cloud after 4 rounds. A strong wind (at least 20 miles per hour) disperses it after 1 round.

At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the radius of the fog increases by 10 feet for each slot level above 5th.