The Archcrusade. Tome One: The Archspawn (en Inglés) - K. M. Hogenson

When bloodthirsty monsters raid the birthplace of the first archangel, the High King of Coserai calls for a crusade to defend the holy land. Basil, a sheltered healing mage's apprentice, marches with the crusade to accomplish his Low King's hidden agenda: to travel to an oracle and gather insight into the fate of the realm. Along his journey, Basil faces threats from demons and criminals, paid to assassinate crusade members. Though Basil's master attempts to spare him from unnecessary suffering, Basil's desire for adventure lands him in danger as he begins to unravel the truth of his divine destiny.