Ciro's Frozen Heart

After a brief incantation, you create a bright orb of green flames in your palm and hurl it to a point you choose within range. The blazing sphere then explodes and each creature in a 15-foot-radius centered on the point of impact must make a Dexterity saving throw. A target takes 4d12 fire damage on a failed save, or half as much damage on a successful one. The fire spreads around corners and stays burning on any solid surface, even if it isn't flammable. It ignites objects in the area that aren’t being worn or carried.

The flames then quickly develop a blue hue and are very cold to the touch. Any creature that starts its turn in the area covered by the flames must make another Dexterity saving throw or else begins to rapidly freeze, unable to move (its speed becomes 0). A failed save allows the creature to repeat it next turn. Two consecutive failed saves result in the creature being covered by a thick layer of ice and Restrained. It cannot attack or cast spells that require somatic or verbal components. Creatures turned into the frozen statue remain Restrained until they pass a Strength saving throw, the spell ends or is dispelled. 

At Higher Levels: When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d12 for each slot level above 4th.