Cecilia's Great and Glorious Middle Finger

With a crude gesture and an explanative, a swirling storm of rocks will circle from the tip of the casters finger to a point you choose within range that will grow in size as they grow closer and explode on impact, sending a spray of prismatic colored debris flying. Every creature within a 20-foot radius must make a dexterity saving throw. A target takes 2d12 fire damage and 2d12 bludgeoning damage and half as much on a successful save. 

Anything that is ignitable within the area will catch flame and the flame will spread. Similarly, there will be a disembodied cackle that hangs around for as long as the fire burns. 

At higher levels. When you cast this spell using a 4th level spell slot or higher, the damage increases by 1d10 for each damage type.