Hydraxon

Hydraxon was a member of the Order of Mata Nui and the jailer of The Pit, an underground prison built to imprison the "unredeemable". However, when Teridax caused the Great Cataclysm, six prisoners called the Barraki escaped and Takadox, one of them, killed Hydraxon and they escaped. Years later, the mask of life used its powers to transform a matoran named Dekar into a new Hydraxon, thus Hydraxon was reborn, but assumed everyone in the Pit was an escaped prisoner.