Star vs. the Forces of Evil - Season 2 Episode 25 -

Glossaryck lets Star pick any page in the book to learn some new magic. Star chooses a mysterious chapter, but Glossaryck tells her it is very dark magic and that he will only let her get a short peek at the page. However, Glossaryck is summoned to the Bureau of Magic; he tells Star not to turn to that page, and his consciousness is dragged away into another dimension. While Glossaryck must deal with a not-so-helpful receptionist and has a difficult time getting to the top floor because the magic system is "on the fritz", Star is tempted to turn the page, and enlists Marco to help do it.