Thandurian Book of Keeping

Thandurian Book of Keeping
Wonderous Item, Legendary

The Thandurian Book of Keeping is one of the legendary books of keeping, and the only one to have ever been found.

At the heart of the Ludof Crisis lies the Thandurian Book of Keeping. The Wizards College in Avalon have kept most details about the event secret, but what is commonly known is that the department of conjuration attempted to summon and control powerful demons on the summit of mount Thandur using this tome, which contains the true names of many a powerful fiend. The experiments failed, and

Draador, a powerful demon prince from the abyss, was released upon the world for a short time.

The book is written in deep speech, the tongue of the infernal. Each entry contains the true name of a fiend. Those that know a fiend's true name can control that fiend against its will, regardless of how powerful the fiend is. Anyone that knows how to read Deep Speech may attempt to read the book. To do so, make a wisdom saving throw DC 25.

On a failed save, the character gains one point of insanity. Once a character receives a point in this way, they spend all their actions attempting to do so. As these points accumulate, the characters demeanor becomes more and more unstable; their appearance becomes dishevelled and their communication is increasingly nonsensical. Once they accumulate a number of insanity points equal to their proficiency modifier, their alignments shifts to chaotic evil. The DC to read an understand the book drops to ten, and the character may only spend their action attempting to summon demons.

On a successful wisdom save, the character learns the true name of a number of fiends as determined by the DM. You immediately know the combat rating of all these fiends, as well as whether or not they exist on the same plane. If the fiend is on the same plane then the speaker may summon the fiend to appear in any square within 5 ft of the speaker. The fiend must follow all directions given by the one which summoned them in this way. The vast majority of names kept in the book of keeping are Yugoloths, though some power demons (such as Draador) and archdevils may be recorded in their as well, but the type and number of fiends summoned is determined by the DM.