The Hummingbird's Tear by C M Kerley

SPFBO9

In the high towers of Castle Kraner the King has chosen to hide away, leaving his kingdom undefended, open to attack from men, monsters and magic users.His loyal son Prince Orren, despairing of his father's wilful ignorance, is doing all he can to gather the men and women he believes can help him avert the war before it starts, to save his land before it needs saving. Brennan and his young brother Calem find themselves drawn to Kraner; as their innate powers begin to manifest and they are woven into the mad schemes of rulers and invaders they must decide what to believe, who to trust, and how far they're willing to go to fight an enemy they can't see.