The Brothers Stryfe (Tales of Anon Book 2)

Before their father left on his ill fated trip to Lothen, brothers Gael and Gabriel traveled to Cabal Island to study the ways of magic. There, they encounter wonders beyond their comprehension. Still, even after news of their father's fall from grace complicates relations with their peers, they must stand against a greater threat. Signs of a dark sorceress's resurrection.