Challenge the Might of the Manas!
The Manas are the most powerful guardians of the evil Makuta! No single Toa can hope to withstand this crab-like beast’s fierce claws — only by combining their powers and skills can the Toa hope to prevail. When they aren’t fighting the enemies of Makuta, the Manas stay combat-ready by challenging each other to awesome battles!
Like all Rahi, the Manas can be defeated by knocking off their infected masks. No one knows if a mask-less Manas can be tamed, however, because no one has ever survived an encounter with Makuta’s guardians.
Source: BIONICLE #3: Triumph of the Toa