You conjure a hunk of sulfuric brimstone that materializes in the air, then falls to the ground at a point within range. Any creature occupying that space must make a successful Dexterity saving throw or take 2d8 bludgeoning damage. The brimstone remains in the space where it fell while the spell persists. Each creature that starts its turn within 15 feet of the brimstone must make a successful Dexterity saving throw or take 1d8 fire damage.   The brimstone can be destroyed; it has AC 8 and 12 hp. The brimstone explodes if it takes fire damage; the explosion ends the spell and deals 1d8 bludgeoning damage to all creatures within 15 feet, or half as much damage to a creature that makes a successful Dexterity saving throw.