The Enchiridion! / The Jiggler

S1 E102: "Enchridion" - Princess Bubblegum tells Finn about a book for heroes called "The Enchiridion". They embark on a quest for the book, and are tested at every turn. "The Jiggler" - Finn and Jake happen upon a jiggly creature who follows them home to their tree house. After some troubles taking care of the Jiggler, they must find a way to return him home to his mother before it's too late.