I'll add some items that weren't mentioned yet:
- If a player puts a book in his backpack, and a typo/error in that book gets fixed, the typo in the older version of the book (in his backpack) remains unchanged, while the book spawning in the bookcase is containing new, fixed text - making such book a rare item.
- Minotaur hill scroll. Unobtainable since not long after 2002.08.28 (update 7.0).
- Before 2005.12.12, author's name and editing date were are not visible. Such scroll/book is a rare, unobtainable item. Between 2005.12.12 - 2006.12.12, only the author’s name was visible. The editing date was not visible. Such scroll is a rare, unobtainable item. History of scroll on Rookgaard (also history of the changes affecting all books and how they display text).
- Document (Fishing Master Certificate). Unobtainable since 2014.09.15 (10.55). It’s no longer possible to enter NPC Santiago’s cellar. Document of the same sprite, name and weight (but different text inside) can be transfered from Dawnport to Rookgaard, some players use it for scamming.
- Premium scroll. Unobtainable since 2015.07.21 (10.80, introduction of Tibia Coins, which replaced the premium scrolls). It was possible to trade this scroll via regular trade window, but the item always stayed inside the purse (old name of store inbox), it was not possible to place it on the ground or inside regular backpack.