The Flamerus Rex is a boss from Final Fantasy Mystic Quest, the Fiend of Earth and one of the Vile Four. It is found at the bottom of the Bone Dungeon, where Benjamin and Tristam challenge it to battle. It is quite powerful with a Rip Earth attack that can be quite devastating as well as several "biting" attacks. However, it is undead and thus highly vulnerable to Cure. After it is defeated, the Crystal of Earth reverts to normal and Tristam gives Benjamin the Elixir needed to rid Kaeli of poison and then claims the Dragon Claw from a nearby chest. Flamerus Rex is later reincarnated as the Skullrus Rex in Doom Castle.