Crown of Shadows by C.S. Friedman
Crown of Shadows brings C.S. Friedman’s COLDFIRE trilogy to a close. (This review may contain spoilers for the previous books, which you really must read before beginning Crown of Shadows.)
In the previous book, When True Night Falls, the unlikely allies Reverend Damien Vryce and undead vampire Gerald Tarrant battled their way across hostile foreign countries to combat the evil force that was threatening humanity.