Copper Mask of Victory
This ceremonial mask is awarded to the champion in village games. As such, it is highly prized by all the islanders of Mata Nui. In an effort to crush the morale of those who resist his power, Makuta has ordered his Rahi to gather the copper masks and conceal them. No one is quite sure where they can be found!
Source: BIONICLE #3: Triumph of the Toa