Vigloo

Duke's son Riven is the capital's most notorious failure. In truth, he's the Nebula Knight who wiped out a demon army alone. As a boy, he learned his stepmother had poisoned his mother, so he has played a drunken playboy until he's strong enough for revenge. Then the emperor holds a tournament for Princess Lyra's hand. When even Riven's brother falls to an invader, Riven finally steps up.