Balthazar's Fury

Empowered by the spirit of the lord of tyranny, you erupt into flames and frost. You magically dash to a creature that you have an unobstructed path to within range. Make a melee spell attack against the target. On a hit, the target takes 4d8 cold damage. Hit or miss, you erupt into flames, and the target and each creature within 5 feet of it, excluding you, must succeed on a Dexterity saving throw or take 6d6 fire damage or half as much on a successful save.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the fire damage increases by 1d6 for each slot level above 3rd.