Adventure Time/Recap/S06/E15 Nemesis

During the meeting of Starchy's Veritas Brigade, a man calling himself Peace Master (voiced by Rainn Wilson) appears and claims that there is a terrible evil trying to consume the Candy Kingdom. Princess Bubblegum, who is spying on the meeting, thinks Peace Master is talking about her. Meanwhile, Peppermint Butler (voiced by Steve Little), fearing that he has been found out by Peace Master, takes to his room and uses a ritual to track down Peace Master and confront him to a battle. Peace Master overpowers him, forcing Peppermint Butler to retreat. Peace Master then challenges Peppermint Butler to a final duel, during which the former loses. By order of Peppermint Butler as the victor, Peace Master leaves Candy Kingdom with Princess Bubblegum being completely unaware of Peppermint Butler's ways.

(Recap copied from Wikipedia, "Adventure Time (season 6)")


 * : defeats.