Forgotten Realms: The Titan of Twilight (Twilight Giants #3)

For untold centuries, a banished titan has lurked in the cold, forbidden dusk of the Twilight Vale—imprisoned for a crime as black as the boreal night. With the birth of a new king comes the titan’s freedom.
 
The Kingdom hangs in the balance as the queen’s consort is forced to choose between his love for his son and the dark prophesy that says his child will unleash a cataclysmic war. But before he can choose, a thief steals both the boy and the choice away from him.