Sister Mask

S1, E5: Stanley discovers a fabled "sister" mask that, when joined with his mask, allows him to control his wild alter-ego. But things go awry when the sister mask reacts unexpectedly and takes The Mask on a wild ride, which includes a mayhem-filled battle with the Army. The Mask discovers Pretorius has built the sister mask in his lab and tricked Stanley into wearing it as a means of remote-controlling The Mask for his own nefarious purposes. In a climactic confrontation, Pretorius' head dons the mask with terrifying results.