The Cerulean Storm

Athas, world of the dark sun: Ruled for thousands of years by power-mad sorcerer-kings, its cities have become vile centers of slavery and corruption. Only heroes of the greatest strength and bravest heart can stand against the might of these overlords. The Prism Pentad is a tale of such heroes.
Rajaat, the First Sorcerer, betrayed by his champions at the moment of his paramount victory, has been imprisoned beyond space and time, but he alone can return Athas to its verdant splendor.
From the Trade Paperback edition.