Cataclysm of Thesroul

The "Cataclysm of Thesroul" is a spell of cataclysmic proportions, wielded only by the most ancient and powerful dragons or by those who have drawn the "Flame" card from the fabled Deck of Many Things. As a 9th-level spell of immense destructive force, it harnesses the primal energies of fire and draconic magic to unleash devastation upon the battlefield. When cast, the caster invokes the name of Thesroul, the legendary dragon of flame, channeling their immense power to summon forth a raging inferno of unparalleled magnitude. Flames erupt from the caster's outstretched claws or hands, swirling and coalescing into a swirling vortex of searing heat and blinding light.

As you cast this spell, your jaw unhinges and your teeth begin to gnarl and crack. From your stomach comes a belch of pure and unadulterated heat and energy as a blast of white hot plasma melts the oxygen around you. You fire out a line of uninterruptible unresistable death that will travel off the face of the earth and endlessly through space for eternity. This spell functions as a 5ft. wide line with infinite range, all targets along the line must succeed a DC 24 Constitution saving throw or suffer 20d10 fire damage and become blinded or half as much on a successful save. This damage cannot be resisted and it ignores immunity. Creatures within 20ft of the line must succeed a DC 21 Dexterity saving throw or suffer 3d10 fire damage, ignoring resistance but not immunity, and become blinded.