A bizarre episode focusing on an alien race called the Tiffin, whose feces turns into literal gold when they consume Earth food. The humor leans heavily into juvenile bathroom jokes, which drastically clashed with the mature sci-fi tone established in the earlier seasons. 40. "Deformed" (Season 3, Episode 9)
A bounty hunter cuts off Ben's left hand—which holds the Omnitrix—sending the hand into the Void while Ben remains on Earth. The physical comedy and split-perspective action sequences make this an incredibly unique, highly entertaining gimmick episode. 24. "Pet Project" (Season 2, Episode 10)
Lore heavy. Ben learns that Chromastone is actually a Crystalsapien – a guardian of the alien race Petropia. Features a duel with Vilgax and the resurrection of Tetrax's homeworld.