The Wrath Of Firneus Fireblast

You Summon Firneus Fireblast, an ancient mage who had a mastery of fire magic unmatched at the time. He will immediately lunge at the target and attempt to detonate himself, Each creature in a 30-foot-radius Sphere centered on that point makes a Wisdom saving throw, taking 8d6 Fire damage on a failed save or half as much damage on a successful one.

Flammable objects in the area that aren’t being worn or carried start burning.

Using a Higher-Level Spell Slot. The damage increases by 1d6 for each spell slot level above 3.