The book recovered from Veyii, the one that both the Baron and Allabar’s friends want, is very hard to read.
On each page is some complex symbol, almost surely a powerful arcane rune. They are accompanied by a dizzying array of annotations, commentary, and other scribblings.
Staring at the central runes on each page is … hard. It starts to hurt a little, and your eyes play tricks on you as it looks as if the long curls of the symbols are actually moving. That couldn’t be happening though.
The introduction to the book includes numerous warnings against reading or analyzing the contents, or sharing the information with others.
Veyii mentions that it is part of The Codex, but does not talk about it much beyond that.