He-Man and the Masters of the Universe (1983)

S2E46 Double Trouble

A violent storm brews around Snake Mountain, revealing a hidden passage beneath the fortress. Skeletor, Evil-Lyn, and Beast Man explore the area and stumble upon a mystical artifact known as the Mirror of Moruvad, which can create evil doubles of anyone. Skeletor devises a plan to capture someone important to He-Man and create a nefarious replica to infiltrate Castle Grayskull and steal its secrets. He targets Koldar, a brave ally of He-Man, who has just arrived for a ceremony at the palace. Using the Mirror, Skeletor conjures an evil version of Koldar, sending it to deceive He-Man. However, Koldar manages to trap Skeletor in front of the mirror, resulting in a heroic version of Skeletor being created, which helps thwart the villain's scheme!