Tanith Lee 
Volkhavaar 

VOLKHAVAAR is a novel of witchcraft and wonders on a world far removed from those we know. Here the gods contend for power — the Dark forces against the Light — and here an entire city and its land is plunged into the shadow of an eil beyond anything conceivable. It is the story of Shaina the slave girl and of Volk the outcast who enslaved himself to cosmic forces to gain total power — and of how they were finally to meet and flash — with an entire world as their prize.