Cataract of Fire

A spell lost to the ages, Cataract of Fire is a 10th level Epic Magic inaccessible to mortals by divine law.

Upon the ring of a bronze gong, an impossibly massive vertical column of arcane fire roars down from the heavens surrounding the caster, both incinerating the caster and mercilessly scorching thier surroundings. Each creature in the 300-foot-radius, 2000-foot-high cylinder must make a Dexterity saving throw. A creature takes 20d6 fire damage and 20d6 force damage on a failed save, or half as much damage on a successful one.

Targets reduced to 0 hit points by this damage are disintegrated. 

The spell confers the caster immunity against all damage except force damage during the spell's casting.

The flames from Cataract of Fire spread in a quarter-mile radius of the caster (1500-feet) at a rate of 60-feet per round. The affected area behaves like the wall of fire spell and persists for 1 hour. These flames cannot be dispelled by an effect of 9th level or lower.

Magical effects within the affected area are dispelled as if within an antimagic field. The area itself becomes a permanent spot of dead magic as the flames scorch the Weave itself. Magical matter, force effects, and energy fields are simply destroyed.