The Tale of Laogeritt the Beautiful
This cheaply-bound softcover book was created by a particularly hideous green hag named Laogeritt, a mage of great power but little sense or self-esteem. Although of a size to be kept in one's pocket, the magic of the book is such that the last twenty or so pages of the book appear blank even though the tale itself is much longer than the pages of the book could possibly contain.
The tale itself is a trite and trashy story of sordid lust and hackneyed sword fights, populated solely by paradoxically bare-chested knights fond of repeatedly proclaiming, "Laogeritt, my Eternal Love, I have come to claim you for my bride!!!" and a princess of astounding beauty whose chaste and virginal attire shows an astounding amount of bare cleavage and seems to get ripped off every three pages. It is also, however, an ongoing magical tale, as Laogeritt created a pocket dimension within the book and then trapped herself within it to live out her somewhat tasteless and gratuitous fantasies for the rest of eternity. Any event that happens within the pocket dimension of the book is simultaneously inscribed upon its pages. As an unintended side effect, anyone reading the story can exert narrative control over the characters by writing a paragraph or two in the book, as long as it is written in the overly dramatic and sordid style of the rest of the tale.
In and of itself, the book is simply a magical curiosity, but it has two rather dangerous abilities: When the book is opened and the opener proclaims, "Laogeritt, my Eternal Love, I have come to claim you for my bride!!!", they and all their possessions are immediately sucked bodily into the pocket dimension of the book and become new characters in the story. (Quite a number of the minor characters, villains and monsters in the book have been created this way, as the book is nearly three hundred years old and many a clever adventurer has had the forethought to point the book at an opponent while declaring their love for the book's main character.)
The second ability of the book is activated when the book is opened and the opener cries out, "Oh, save me, my Brave and Handsome Knight!!!", upon which a random occupant of the book is released back into the world - who may or may not decide to stick around and fight, either for or against the person who released them.
As near as the sages have determined, there are only two ways to release a specific character from the book - by writing them out of the story in such a fashion that Laogeritt wishes never to see them again (which ejects them violently from the book), or by entering the book and convincing Laogeritt to release them voluntarily.
The sages have also determined that destroying the book or killing Laogeritt will likely release EVERY character in the book... Which would be... bad.
A small wooden box, the top sealed with glue, whose gold lettering proclaims that it holds within it The Wonderous Whatsit of Woldew Wigglefingers (whatever that is)