Glacial Fog

As you cast this spell, a 30-foot-radius sphere centered on a point within range becomes covered in a frigid fog. Each creature that is in the area at the start of its turn while the spell remains in effect must make a Constitution saving throw. On a failed save, a creature takes 12d6 cold damage and gains one level of exhaustion, and it has disadvantage on Perception checks until the start of its next turn. On a successful save, the creature takes half the damage and ignores the other effects. Stored devices and tools are all frozen by the fog: crossbow mechanisms become sluggish, weapons are stuck in scabbards, potions turn to ice, bag cords freeze together, and so forth. Such items require the application of heat for 1 round or longer in order to become useful again.