Amethyst of the Gods — Richard S. Tuttle

A hundred-thousand man Lanoirian army is poised outside the walls of Melbin in a bid to attack Alcea from the south. Meanwhile an enormous army of goblins, yaki, ogres, and Black Devils are heading towards Tagaret, the capital of Alcea, from the north. King Arik and his Alcea Knights must defeat these two armies to complete the Ancient Prophecy. The immortal Mage has gathered six of the world's greatest magician to embark upon a mysterious mission that appears to be at odds with King Arik's fulfillment of the prophecy. The stakes have never been higher, nor the situation ever so dire. Amethyst of the Gods is the final volume of the Sword of Heavens series.