The Divine Talisman: Book Three of the Legend of Asahiel

To protect his people from the demonic Illysp, Torin, king of Alson, made the ultimate sacrifice. Now his best friend and his former love seek to salvage the shattered lands beyond their borders. But a treacherous assault costs them their most powerful weapon—the fabled Crimson Sword. Hopelessly outmatched, Pentania's citizens must flee their conquered homeland or else perish. And now the Leviathan has been awakened—an unfathomable creature whose wrath could single-handedly destroy the entire world. Scant hope remains—save for the possibly futile efforts of a lone elf, a mad witch, and a fallen hero charged with unraveling a series of divine riddles. But doom is inevitable, unless they can somehow break the powerful bonds of a fiendish, insidious possession.