Voltron: Defender of the Universe: The Complete Series
Voltron: Lion Force, Yurak Gets His Pink Slip
S1 E14:
The Voltron Force successfully ground Yurak's fleet for the last time. King Zarkon is ready to banish Yurak, but then his son, Prince Lotor, returns from his journey of conquest. Prince Lotor turns Yurak into a Robeast, and then challenges Keith to a duel. With Keith away from the team, they are forced to fight Yurak without the help of Voltron!