Chilling Cloud

You create a 20 foot radius sphere of freezing blue fog centered on a point you choose within range. The fog spreads around corners. It lasts for the duration or until strong wind disperses the fog, ending the spell. Its area is heavily obscured. When a creature enters the spell’s area for the first time on a turn or starts its turn there, that creature must make a Constitution saving throw. The creature takes 4d6 Cold damage on a failed save, or half as much damage on a successful one. The fog moves 10 feet away from you at the start of each of your turns, rolling along the surface of the ground. The cold fog, being heavier than air, sinks to the lowest level of the lands. 

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d6 for each slot level above 4th.