The Sincerest Form of Flattery - S1.E31

Unable to contain his ambition, Lotor challenges Zarkon to a duel in the arena. The winner takes the throne of Planet Doom. Witch Haggar takes the opportunity to steal the spotlight and field her anti-Voltron robot, programmed to steal the spotlight and exploit Voltron's weaknesses. Concentrating all its fire on Blue Lion, the robot successfully hands Voltron his first defeat!