Cloud of Blindness

You create a 20-foot-radius sphere of dark fog centered on a point within range. The sphere spreads around corners and its area is heavily obscured to anyone trying to see from outside. Any creature within the fog is considered blind. It lasts for the duration or until a big gust of wind disperses it. 

May Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the radius of this spell increases by 20 feet for each spell slot above 1st.