Rise of a Guardian by LJ Andrews

Abandoned by his family as a young child, Killian Thomas is given one chance to find answers to his past in a strange realm.
A mysterious community, bound to protect the realms, promises to help him on his quest if he aids them in a desperate search for powerful lost relics. Each relic possesses magic of all four realms, giving their owner unimaginable power.
Strange abilities soon manifest within Killian, catching the deadly attention of a dangerous secret-society intent on destroying his home realm.
Killian must find the relics before the society or countless innocent lives will be lost, but sometimes the closest allies are the most devious enemies.