Cerberus is a Sub-Boss in the Hall of Malice. It could help to throw Sub-Weapons at them, like Bombs or Shurikens.

When entering the room, make sure you run and jump to the platform to the right as soon as you see the door on the right start to close: Cerberus jumps into the room, and it's easy to get hit upon their entry.

When Cerberus' health bar reaches 0, they enter a panic state with another form. You could try throwing Earth Spears or Shurikens at it in-between its attacks.