"By the Book" is the second segment of the twentieth episode of Star vs. the Forces of Evil. It premiered on September 12, 2016 alongside "Goblin Dogs", and is the second segment of the seventh episode in the second season.
Star has not been following the advices of Glossaryck when it comes to mastering new spells causing the two of them to have a falling out. Marco does various things in order to get Star and Glossaryck to reconcile. Meanwhile, Ludo hears the voices from within the wand that tell him what he needs to master his wand.
- Eden Sher as Star Butterfly
- Alan Tudyk as Ludo
- Adam McArthur as Marco Diaz
- Jeffrey Tambor as Glossaryck
- October 6, 2016 (United Kingdom and Ireland)
- November 15, 2016 (Italy)
- December 18, 2016 (Japan)
- December 22, 2016 (Latin America)
- January 10, 2017 (Poland)
- January 13, 2017 (Southeast Asia)