Wheel of the Infinite (Updated and Revised Edition) - Martha Wells

A traitor and a swordsman join forces to save the world from being rewritten into devastation.Every year the image of the Wheel of the Infinite must be painstakingly remade to ensure another year of peace and harmony for the Celestial Empire. Every hundred years the very fabric of the world must be rewoven. Linked by the mystic energies of the Infinite, the Wheel and world are one. But a black storm is spreading across the Wheel, reappearing each morning, bigger and darker than before, unraveling the beautiful and orderly patterns.Maskelle, a murderer and traitor, has been summoned back to help put the world right with the assistance of the mysterious Rian, a swordsman of some renown. If they can’t find the source of the problems that plague the Wheel, the world may find its latest rotation is its last.