Magmorak: The Lost Fire.

When a forgotten war god is sealed inside a necklace and dropped into the lap of an ordinary kid, the balance of magic starts to crack. Jim Lake, a quiet nobody from Asphalt Island, becomes the unlikely vessel of Magmorak, the Guardian of War and Fire. Hunted by cosmic forces and guided by ancient guardians, Jim must master a god's power before it burns him alive. Magmorak: The Lost Fire is a high-stakes fantasy about war, magic, and the price of power in a world built by elemental gods.

Link: www.wattpad.com/1550515869-magmorak-the-lost-fire-magmorak-tlf-chapter-one