Blast Burn

A bright streak flashes from you to a point you choose within range and then blossoms with a low roar into a destructive, fiery explosion. Each creature, structure, and object that isn't being worn in a 30-foot-radius Sphere centered on that point makes a Dexterity saving throw, taking 5d10 Fire damage on a failed save or half as much damage on a successful one.

The blast deals 15 Bludgeoning damage to any structure in the area when you cast the spell. If a structure drops to 0 Hit Points, it collapses. A creature within a distance from a collapsing structure equal to half the structure’s height makes a Dexterity saving throw. On a failed save, the creature takes 12d6 Bludgeoning damage, has the Prone condition, and is buried in the rubble, requiring a DC 20 Strength (Athletics) check as an action to escape. On a successful save, the creature takes half as much damage only.

Creatures, flammable objects and structures in the area that aren’t being worn or carried start burning. Burning targets take 2d10 fire damage at the start of initiative count 20 each round instead of the normal damage for burning, and can only stop burning on a successful Dexterity saving throw against your spell save DC. 

Using a Higher-Level Spell Slot. The initial damage increases by 1d10 for each spell slot level above 4.