The Nether Scroll (Lost Empires #4)

Ansoain has been murdered, and her son Galimer taken hostage.
Druhallen, a young magic user, must avenge the murder of his teacher and rescue her son from a dubious fate. But not everyone is telling Druhallen the truth.
Druhallen and his companions must brave the ruins of Dekanter to find a missing artifact . . . the Nether Scroll.
Without the Nether Scroll Galimer may die. With it Druhallen may go mad.