When True Night Falls: Coldfire Trilogy, Book 2 (Unabridged‪)‬

Two men, absolute enemies, must unite to conquer an evil greater than anything their world has ever known. One is a warrior priest ready to sacrifice anything and everything for the cause of humanity's progress; the other, a sorcerer who has survived for countless centuries by a total submission to evil. In their joint quest, both will be irrevocably changed.