Jinxes for the Jinxed is a collectible book. It can be found in Harry Potter and the Order of the Phoenix, Chapter 27, "Patronuses in the Room of Requirement".
Description[]
| “ | Learn some jinxes to add to your arsenal with this handy volume | ” |
Location[]
The book can be found in "Patronuses in the Room of Requirement" on the first zoom level, on the shelf between Hermione casting her otter Patronus and the wizard casting a swan Patronus.