Twilight Haze

You create a 40-foot-radius sphere of grey haze centered on a point within range. The sphere spreads around corners, its area is heavily obscured, and the illumination level within the sphere drops one step. It lasts for the duration and, since this spell produces an illusion rather than a true physical fog, it is unaffected by wind and can be cast underwater.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the radius of the haze increases by 20 feet for each slot level above 2nd.