From the introduction: In this book you will find listings of every potion in the Harry Potter universe. For the most part, preserving canon will not be this book's first priority, but rather to provide potions which enhance the game and your roleplaying experience by providing as many useful concoctions as possible. Every potion which it is felt should be accessible to players can be found in this book, canon or not. However, every non-canon potion will be marked with an asterisk so that if you wish you may exclude such potions from your game.