Devil Vadriel is the true final boss of Sonata of Blood. It is a massive horned demon with long wings, resembling a tiger. This represents one of Vadriel's main symbols, a cat. He is about 30 times the size of a normal human.
Vadriel will start out the battle by slashing with his claws. His bite is extremely dangerous, and can inflict both poison and curse status at the same time. He can also whirl around the battlefield to get closer to the player. His tail will poison, and he can shoot meteors from his mouth. His weak point is his glowing eye, which can shoot flames. To get to it, the player must jump onto Dracula's Throne, grapple whip onto a bone, and fly right into Vadriel's eye. When damaged enough, the eye will stop glowing, and another phase will begin. He has 1000 HP in this phase. The theme of this phase is The Blue Dragon.
Now, the player must destroy Vadriel's power source. He has his previous attacks. They must lure him to the glowing crystal, and get him to shoot a meteor. They must hit it, making it fly into his power source. He has 2000 HP in this phase. The theme of this phase is The Grey Knight.
Now, Vadriel's weakness is revealed, on his back. He has his previous attacks, as well as a dash attack and a life steal. The player must make him dash into boss remains, so he will get stuck. There, they must grapple onto his tail, kick onto his back, and attack him with the Fury Blade. However, he will attempt to knock them off with his tail. After he gets loose, they will automatically be knocked off. Near the end of the battle, he has a lightning attack. After defeat, he will cast Giga Demonic Meggido, which can be prevented with Dominus. Vadriel has 9000 HP in this phase, equaling 12000 HP in all. The theme of this phase is Judgement of Darkness.
After being hit by Dominus, Vadriel felt a rush of pain, gave his final words, and stumbled backwards, getting impaled on an iron spike.