Termitball

You summon a hot ball of fire, made of a boiling mixture of rust and metal.
Each creature in a 10-foot-radius centered on a point within range must make a Dexterity saving throw. A creature takes 6d8 fire damage on a failed save, or half as much damage on a successful one. 
The pile of semi liquid termit stays on the ground for 1 minute and burns all creatures within the radius for 2d8 fire damage when they start there turn within range. 

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d8 for each slot level above 4th.