Draconic Inferno

An exceptionally powerful spell, the Draconic Inferno conjures a spectral great fire dragon, made of flame and smoke, flying to an area of the caster's choosing and spraying a torrent of fire, circling an area of at least 500 ft, and up to 2000ft. The spectral fire dragon will carpet-burn the area for one minute, then explode violently into the ground, destroying anything large like a building, tearing it apart - or entirely incinerating it into ashes if made of flammable material, leaving little to no trace the structure existed. The explosion covers an area of 100ft.

Upon casting, roll 12d12 for damage + spellcasting modifier - Wisdom, Charisma or Intelligence. Every living thing must roll a Dexterity saving throw. On a failed roll, they take full damage and are set ablaze. A successfull roll halves the damage and they will not be set ablaze. The explosion causes an additional 5d10 damage and cannot be avoided.

This counts as a Level 9 Spell Slot. For each level below, remove 1d12 from the damage roll and add 1 Level of Exhaustion to the caster, up to 5 less rolls and 5 Levels of Exhaustion. All spell slots above level 4 are locked until a long rest, no matter which spell slot is used to cast the spell.

After the spell has run it's course, residual flames will linger for a full 7 days unless intense cold or other efforts are made to put them out. Anything flammable will either burn down or the fire eventually subsides.