Magic Item - The Book of Deeds

The book weighs 5 lb. and features a black leather cover with golden letters reading "The Book of Deeds" and gold leaf pages. Abstract gold figures decorate the spine. The book gives off a faint smell of myrrh. If you look at the book out of the corner of your eye, you get the sense that it is slowly expanding in size or moving closer to you, even though this is clearly not the case. The book is kept closed by a simple lock covered by a red wax seal depicting a stylized sun. The lock is easy to pick or break. The pages are blank until the book is opened, but it would obviously be difficult to determine that without opening the book and triggering its effects.

The first person to open the book determines its contents. If an NPC is the first to open it, the pages will be filled with descriptions of various events that have taken place in that NPC's past. The descriptions will generally revolve around the most morally right and most morally wrong actions that the NPC has ever taken. Since morality is at least partially a matter of belief or opinion, exactly what choices count as the most morally "right" or "wrong" among all those ever made by the NPC should be determined by how glad or ashamed (in a moral sense) the NPC is to have made such choices (or to be reminded of them by the book). If the NPC is not capable of feeling gladness or shame regarding matters of ethics, or if they can feel these emotions only in a very shallow sense, or if they are simply incapable of knowing right from wrong, the NPC's actions depicted in the book will be those which would generally be considered the most righteous or depraved among the NPC's peers, community, or associates.

If a PC is the first to open the book, it contains the actual play reports of all campaign sessions involving that character up to that point. You can be "meta" and have the wording in the book literally be the same as in the actual play reports, possibly causing any readers to discover that they are living in an RPG, or you can just use the actual play reports as a guideline for determining which events are depicted in the book, and thus avoid any issues of breaking the "fourth wall." Either way, the book's sole contents are descriptions of what the PC did in the past, along with any other characters who were present, of course.

At the instant the book is opened, a second copy of the book also appears out of thin air somewhere else in the world. The DM can determine this location randomly, or just place it in a spot that will result in the most interesting, entertaining, or complicated situation for the players. If you have a world map, you could maybe drop a die on it and put the copy roughly where it lands. Don't put it somewhere that will automatically and completely ruin the party's chances of survival or success, though; they should have a chance to find out the book is out there and try to recover it if they so desire...at great cost and with great difficulty, of course.

EDIT: If you can't think of another way for the party to find out that the copy is out in the world, you could just have the final paragraph in the book describe the new copy appearing, with vague hints as to where it is or who might find it.

After 24 hours, the pages of the original book become totally blank if that book is closed for even an instant. The copies, however, are mundane books with contents that are not automatically erased. Once the book has become blank, the next person who opens it will trigger its effects again.