The Dn'i Art of Writing can be used to control the Age's contents, by choosing and arranging its Symbols. A Descriptive Book's destination is always the world spawn, a 5x5 platform of Stone with a few blocks of open space overhead, of that Age.
To use the Descriptive Book, right click with the book to open it and then click on the picture on the second page. If the player uses the book by hand, the book is left on the ground and is susceptible to damage by the environment (rain, water, etc.) or players. Much like a Boat or Minecart, moving into the Book will push it around. The book can be picked up again by shift right-clicking on it. To prevent the Book from being left on the ground, it can be placed on a Bookstand or Lectern.
If traveling to a new Age, it is very important to bring a Linking Book linked to the Overworld in order to be able to return. If Draconic Evolution is installed, the Enhanced Charm of Dislocation can be used to teleport back.
A Descriptive Book which has not been used yet is not completely active—it cannot be used for a Portal, and if Blank Pages have been written into it, they can still have Symbols written onto them. The link will need lots of time to be completed when the Book is used for the first time, as the world is being created while the player falls through the void.
Using the use key on the Book (in hand or in world) will open its GUI.
Inside the front cover is an inventory slot containing the book item; when this is picked up, the player's inventory will become visible, and the book can be placed there. With a free inventory slot, it is also possible to quickly pick up a Book entity, or take a Book out of a Bookstand/Lectern, by sneak-using it.
On the first page of the book, the Link Panel will be visible. Clicking on the Link Panel will cause the player to link. They will appear to be falling through void (without their inventory) for some time, until they (and their inventory) rematerialize at the spawn position. The time required will vary, as it is used to load the destination chunks.
If the LookingGlass mod is installed, the Link Panel may give a view of the destination. This view will not show mobs or other entities, and is not available at all for an unused Descriptive Book.
The Descriptive Book is created by putting the Link Panel and any Symbols used into a Book Binder. A book created with no Symbols (only a Link Panel) will lead to a completely random world, which is likely to be dangerous.