The Librarian provided three types of bookmarks: Invasion Bookmarks, Guardian Bookmarks, and Revenge Bookmarks, each type having only a stock of two.
Strangely, Lin Xun didn't see any price tags on these bookmarks.
[The Librarian tells you that Apostles need a healthy competition to bring out their greater potential. Therefore, he provides the three types of bookmarks for free use by the Apostles.]
[However, excessive rivalry can turn competition into a destructive force; hence, the bookmarks provided have a quantity limit.]
[Of course, if you feel the competition is not intense enough, you may choose to pay a small price for additional bookmarks...]
The bookmarks provided by the Librarian can't be traded in the Book of Trade, and can only be exchanged in person, offline.
Each type of bookmark only has a stock of two. After being taken, if one still wants these bookmarks, they have to manually replenish the stock with spiritual energy.