For centuries, two nearly-immortal races-the Krotanya, followers of Light, and the Leishoranya, servants of Darkness -- have been at war. Both races use mental powers in addition to the sword and bow. But because of their moral scruples--the Krotanya use their powers only to defend, not to attack -- they have suffered defeat after defeat and been driven deep into their ancestral lands.
Used availability for Nancy Asire's Twilight's Kingdoms
November 1987 : USA Paperback