Duna's Firework Fountain

The caster throws the pinch of ash and iron into the air which explodes in a Firework Fountain. each creature, of your choice, within 20 ft. of must make a dexterity saving throw. On a failed save the creature takes 3d8 fire damage, or half as much if they succeeded, as the firework rains down on the creature.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher,  the damage dealt to each creature increases by 1d8 per level above 2nd.