Desertification

Pick a point within range - a 15 ft. sphere around that point instantly becomes an arid, desert-like biome. Any creatures inside the range must make a Constitution saving throw, taking 2d8 fire damage on a failure. Failing 3 of these saving throws in the same instance of a spell causes the creature to gain 1 level of exhaustion.

With each level this spell is upcast, it gains 1d8 additional fire damage.