D.M. Cain 
The Shield of Soren [EPUB ebook] 

Young Soren is the apprentice of legendary warrior, Raven Lennox. At the age of sixteen, Soren is expected to fight in the eternal war against the Brotherhood of Shadow – but he seems to be more interested in mischief than battle.
When one of Soren’s adventures goes off course, he accidentally unleashes a deadly threat. As an age-old prophecy comes to pass, Soren must take a perilous journey deep into enemy territory.
But does he have what it takes to save the realm, or will the Brotherhood destroy everything he loves?