The first book of dooms - Mark S. Smylie

In the Highlands of the Middle Kingdoms, where witches and warlords vie for power, a warrior-priestess named Artesia fights for her King against the rules of rival citadels. The Highlands of Daradja are dotted with ancient citadels and castles, held by petty kings and clans that war against each other and the brigand bands that plague the bleak mountains and valleys. Artesia, once a concubine to King Branimir of the Citadel of Dara Dess, has in time risen to become one of his chief war captains; a priestess to dread goddesses; and a magician like her mother once was, controlling warlike spirits. She and her captains carry the cause of their King against his enemies in the field, but afraid of her growing power, her King betrays her and takes new allies: knights from the neighboring Middle Kingdoms, who follow a foreign god, the Divine King, and persecute witches. And in the middle of betrayal and tragedy comes word that the Middle Kingdoms have been invaded by an ancient enemy to them all, the Empire of Thessid-Gola...