Voltron: Defender of the Universe

Lotor fails to capture Planet Arus and allows the Voltron Force to capture the Pulsar Cannon. For his incompetence, King Zarkon has his son imprisoned! Princess Allura and her alliance of local planets see their chance to launch a counterattack on Planet Doom itself. They disable Planet Doom's shield with a shot from the Pulsar Cannon, only to be faced with the ultimate Robeast: King Zarkon himself!