Cerber is a large demon with a dog head, and two other heads attached to his arms - red cow head that spits red mist and blue goat head that freezes Belial. His 'main' head attacks by spitting acid. He has multiple bandages on his legs, a belt with skulls and a large spiked collar on his neck. His skin is greyish-blue.
At first, Cerbeus will send Beasts to attack the player, and those should be dealt with first. To defeat the demon, one has to destroy it's heads in a specific order, indicated by the health bar image on top of the screen - first the red head, then the blue one, and finally the middle one. After each head is destroyed, the boss will summon new waves of Hellhounds.