The Mask: Animated Series (1995)

S1E5 Sister Mask

Stanley stumbles upon an legendary "sister" mask that, when combined with his own, grants him the power to harness his unruly alter-ego. This newfound ability presents both opportunities and challenges as he navigates the complexities of his dual identity. With the sister mask in hand, Stanley must learn to master his wild side while facing the repercussions of his choices.