Un’Jaguk is the toa possessing the mask of metal. Him and Exetriz are the forgotten toa. B.T.W; an Exetriz moc is on the way.
While the MOC is simple I think it looks nice. Asymmetry can be good when utilized correctly, and the armoring looks pretty good here but I would recommend finding something to cover up the exposed CCBS bone on the left leg.
The armor is left off of that leg to keep the robotic/inorganic feel of the character.