Harry Potter and the Half-Blood Prince (2009)
If we suddenly started following the scrawled instructions of a bloke called the 'Half Blood Prince' in a potions textbook, we'd be in a padded room before long. Harry Potter takes his chances though, and his potions grades shoot through the roof. Though he'll probably regret trying out some of the mysterious spells. Remember kids, don't touch homemade incantations without adult wizard supervision.