Years ago, the Voltron Force ultimately defeated Prince Lotor, resulting in h...
Voltron: The Third Dimension
Season 1 Episode 7: Bride of the Monster
Lotor kidnaps Judge Armistice, whose signature is needed for a peace treaty. Haggar then uses her magic to make Lotor look like his old self. All he needs now is to get Allura to Castle Doom to make her his bride.