"Subterranean"

Subterranean was a Onu-Matoran and Dark Hunter.

Toa\Dark Hunter War
During the Toa/Dark Hunter war in Metru Nui, an Onu-Matoran was trapped in an Archive tunnel when it collapsed. Over time, he somehow mutated into his current form. It is likely that he was mutated by a substance in an archives display case, possibly a mutagen.

Dark Hunter
After escaping from the tunnel, his new form scared his friends, and in grief he left the city with the Dark Hunters as they were expelled from the city after the war.

Powers
Subterranean can disassemble objects by touching them, and can immobilize enemies just by looking at them. His major weakness is sound, as even the slightest whisper is painful to him; he wears special armor that dampens sound to compensate. He is currently trying to arrange an alliance between the Hunters and a tribe of Frostelus on the grounds that he is one of the few creatures uglier than they are.