Alduin's Icy Hot

You rub your hands together and thrust them forward towards a point you choose within range that erupts with a tempest of fire and ice. Each creature in a 10 foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 4d6 fire damage and 4d6 cold damage on a failed save, or half as much damage on a successful one.

The sphere spreads around corners. It ignites flammable objects in the area that aren't being worn or carried. The ice turns the terrain into difficult terrain for the next minute or until cleared.