Liber Daemonicum
The Liber Daemonicum (aka Libra Daemonicus) is the Grey Knights Chapter's sacred book that contains prayers, battle rituals, litanies, funeral rites, and Chaos lore. It is THE big book of all things Heretical and is the most important piece of equipment that each Grey Knight owns.
Overview[edit]
Inquisitors of the Ordo Malleus are also known to posses copies of the book which is no surprise given they work with the Grey Knights. While it may appear to be a normal book, opening it will reveal a series of flickering paper-thin screens that contain interactive information that can be brought to focus or enlarged. Page after page discusses tactics and how to fight the denizens of the Immaterium, as well as, listing the True Names of a great many Daemonic entities; information collected from the Librarium Daemonica, the repository of dangerous knowledge pieced together by the Ordo Malleus over the millennia. So imagine, if you will, a multi-stacked tablet, it is pretty cool all things considered.
The book also pulls no punches; it includes an extensive discourse of when to terminate compromised allies and a whole chapter discussing the moral implications and appropriate use of Exterminatus.
Each Grey Knight fights with a copy of the book displayed in a beautifully decorated ceramite case fastened to his breastplate or hanging from a chain around his neck. It contains exactly 666 words which is fucking ridiculous as that is barely over half a page, so it is most likely a typo and they meant 666 pages. The book is also represented in Grey Knight iconography, on the chestplate and pauldron of both power armour and Terminator Armour. It should also be noted that the book itself is kind of small, dimensionally at least. If the Grey Knight Paladin model is any indication, the book is more like a booklet; being roughly the size of a notebook. Have fun seeing a 8-foot tall power armoured-clad giant reading a book no bigger than his palm.