Kingdom of Shadow — Richard A. Knaak

Since the beginning of time, the angelic hosts of the High Heavens an
the demonic hordes of the Burning Hells have been locked in a struggle for the fate of all Creation. That struggle has now come to the mortal realm...and neither Man nor Demon nor Angel will be left unscathed....

Legend-speaks of a long-dead city known as Ureh, thought by many to have been a gateway to the High Heavens. It is believed that every two thousand years, when the stars align and the shadow of Mount Nymyr falls upon the ruins, Ureh is reborn--and all its lost riches are revealed to those brave enough to seek them out.

Now, after a lifetime of research and intense calculation, the'Vizjerei sorcerer, Quov Tsin, has come to witness Ureh's rebirth for himself. But that which awaits Tsin and his hired band of mercenaries is nothing like what they expected. They will find that the dream of radiant Ureh is, in fact, a twisted nightmare of horror--one that will draw them inexorably into THE KINGDOM OF SHADOW