Grimoire of True Names
A Grimoire of True Names is a book in which is inscribed the true names of all the daemons encountered and recorded by the Ordo Malleus. Knowledge of a daemon's true name grants some measure of power over that daemon. True names are, however, usually completely alien and very nearly unpronounceable.[Needs Citation]
A copy of the Grimoire exists within the Warp, where it is of great value for Daemons in battling one another within the realm of Chaos. Whilst a Daemon possesses the tome, he not only has command over his fellows but can also channel the power of the Warp to invigorate and nourish them.