Dragon Spite

The spell is centered on the caster for a range of 20ft. The caster ignores all damage from the spell. A fountain of churned earth erupts in a 20ft circle around the caster. Each creature in that area must make a dexterity saving throw. A creature takes 3d6 bludgeoning damage and 3d6 fire damage on a failed save, or half as much on a successful save. The ground surrounding the area becomes difficult terrain until cleared.  Each 5-foot-square portion of the area requires at least 1 minute to clear by hand.

When a creature fails the spell save, they are also knocked prone. 

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