Cataclysmic Sphere

You call forth the four main elements (Fire, Air, Earth, and Water) and hurl an orb of raw elemental power at a point you choose within range, which then blossoms into an explosion. Each creature in a 30-foot radius sphere centered on that point must make a Dexterity saving throw. A target takes 8d6 force damage on a failed save, or half as much damage on a successful one.

On subsequent rounds, you can use your action to increase this spell's level by 1 higher than your available spell slots. If you do so, you gain 1 point of exhaustion for each subsequent action used to increase its level in this way. Also, if you take damage during the casting of this spell, you must make a concentration check or take 4d6 force damage, as the raw elements spiral out of your control.

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