Coros's Freezing Fog

A cloud of subzero fog appears at a point you can see within 150 feet, obscuring vision and inducing frostbite. The fog occupies a cylinder with a radius of 20 feet and a hight of 20 feet. The fog spreads around corners and its area is heavily obscured. It lasts for 1 hour and a wind of moderate or greater speed (at least 10 miles per hour) pushes the fog at a speed of 5 feet per round, which increases by 5 feet for every additional 10 mph.

Unless a creature within the fog has resistance to cold damage or is able to resist the effects of temperatures as low as −50 degrees Fahrenheit, its movement is reduced by 10 feet within the fog and it takes 2d6 cold damage when it ends its turn there.

If a creature within the fog is reduced to 1 or fewer hit points, it becomes petrified in ice. A petrified creature that is not dead is immune to cold damage and can have its hit points restored by magic. It can be freed from the ice by melting the ice normally. In temperatures of 75 degrees Fahrenheit, a medium creature will thaw in about 8 hours. As the ice melts, a creature takes 1d4 cold damage.

If this spell is cast in the same location every day for 30 days, the effect becomes permanent; according to the lowest level of spell slot used in any of the 30 castings of the spell at that location. If a wind of moderate or greater speed blows toward a permanent freezing fog, it is magically blocked from entering or moving the cloud.

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