ThunderCats Episode 1.01 The Sword of Omens

Lion-O who is constantly being outdone by his adoptive older brother Tygra discovers that he has been chosen by the Sword of Omens to be the next king. Despite controversially setting enemy slaves free, Thundera is attacked. It is soon found out that this was organized by a friend of the current King of Thundera, and that Panthro (previously thought to be dead) was being held hostage. Lion-O, and Tygra escape imprisonment after finding a seemingly intentionally placed key in a bowl of gruel. They find Jaga being interrogated by Mumm-Ra who is the evil leader of the army, who's intention was to gain control of the Sword of Omens. Lion-O Grabs the sword and summons its full power, blasting Mumm-Ra out into the sun where he is seen burning. Cheetara is found by them, and with Jaga defending them with his life the three of them escape seeing their home in ruins despite knowing that this is only the beginning of their journey.