At least some content in this article is derived from information featured in Harry Potter: Hogwarts Mystery. Spoilers will be present within the article.
This book is a literary work published sometime before 1984 and centring around introducing the novice wizard or witch to various spells and potions that could be used defensively and offensively in duelling. At least one of the four houses at Hogwarts owned a copy of this book, which they kept safely hidden away in in the Artefact room.
During the 1984–1985 school year, the new Prefect in the house that Jacob's sibling was sorted into decided to teach the new first year how to handle themselves in a duel as means of self-defence, in light of how they were being frequently bullied and threatened by fellow the first year in Slytherin House, Merula Snyde. Having studied both various duelling techniques and strategies as well as contemporary history in it about notable accomplished duellists, this book was a great help for said student to become an accomplished duellist themselves, and most likely continued to benefit successive generations of students in that house in similar situations.
Behind the scenes
- It seems that, based on the player's House, this book is owned by one of the four Houses of Hogwarts.
- Since the book discusses duelling techniques and strategies, it is possible that it is an in-universe guide to the "rock, paper, sizer" setup of duelling in the game, noting from a dueler's perspective how an aggressive spell-caster can often be fended off by a sophisticated defensive response, and that while a sneaky approach to duelling is indeed useful in terms of finding a way around an opponent's defences, a bold spell-caster can overcome such a method by forcing their way through said approach, and discuss the pros and cons of all three. More so than merely being instructive in how to use defensive and offensive combative spells, it also seems to cover historical accounts of notable duelists in history and their feats, seen as how Rowan Khanna discovered that Professor Flitwick, the school's Charms Master, was a former Duelling Champion while reading it.