Ash Torrent

You create a 20 foot cube of thick gray ash at a point within range. The Ash can spread around corners, and its area is heavily obscured. Any creature within the area is blinded while they are within. It lasts for the duration or until a wind of moderate or greater speed (at least 10 miles per hour) disperses it. The ash itself is flammable, if it comes in contact with flame or is otherwise ignited the entire space becomes a blaze and is dispersed. Any creature within the blaze must make a Dexterity saving throw or take 4d8 fire damage on a failed saving throw, or no damage on a successful save. 

At Higher Levels. When you cast this spell using a spell slot of 4nd level or higher, the size of the ash torrent increases by 10 feet for each slot level above 3rd.