Brimstone

Choose a point of earth you can see within range. The earth crumbles and is engulfed in magma and brimstone. each creature in that area must make a dexterity saving throw. A creature takes 10d6 fire damage on a failed save, or half as much damage on a successful one. The earth affected by the spell also becomes difficult terrain until it cools after 1d4 days.

At Higher Levels. When you cast this spell using a spell slot of 5th or higher, the damage increases by 2d6 for each slot above 4th.