Corrupted Books of Dispater

Corrupted Books of Dispater Wonderous item, artifact, (requires attunement be a fiend or half-fiend)

The Books of Dispater were originally created around 1100 St by the archdevil Dispater. He made nineteen books that he gave to nineteen of his erinyes generals. These books worked twofold. Firstly, they acted as arcane spellcasting foci for his generals. More importantly, they allowed near instantaneous communication without costing the generals their arcane power. The books worked such that anything written on their pages appeared in the other books, with a slight mental ping that alerted the attuned creature when a message had been written. Messages could only be written using arcane means (prestidigitation, illusory script), and faded after a few hours. To ensure the secrecy of the devils' communication, only those of fiend blood could attune themselves to the books, and only attuned creatures could read the words. Anything written would be readable by the attune creature, even if the creature did not understand the language in which the message was written.

In 12 Ws, the erinyes Elota was slain, and her book scavenged by the quasit Grz'Kriit. The demon enlisted the help of an arcanaloth to understand and warp the book's properties. The book ceased to function as an arcane focus unless an excerpt was read from it as the spell was cast. Furthermore, the messages became delayed in their arrival anywhere from a few minutes to a few days. Grz'Kriit began to write flavourful poetry into the book to enrage the devil who still had their books.

The book's corruption spread through the arcane link that tethered all nineteen books together, infecting the entire set and rendering them useless to the armies of Dispater. As they were difficult to destroy, the books were simply abandoned, their power posing no threat to anyone anymore. Several of the books now reside in the custody of demons, while the others travel from owner to owner, seemingly drawn to those of a chaotic nature.

Random Properties. Spellcasting. The book can be used as an arcane focus while you are attuned to it. When using an action (but not a bonus action or reaction) to cast a spell, you must read an excerpt from the book beforehand. This excerpt is often in the form of short two-line poem, and can be provided by you or your DM. Reading the poem becomes the verbal component of the spell. If the spell being cast does not have a verbal component, it gains one. You must be able to see the open book in order to read from it. As long as you can read a language, you can read from the book.
 * 2 minor beneficial properties
 * 2 minor detrimental properties

Linked Pages All nineteen books share an arcane link. Words magically written into one book by anyone will appear in each book. However, the words may take up to 2 days to appear, and can appear in different books at different times. When a new message appears in your book, the book alerts you with a mental ping in your mind. The ping does not wake you if you are sleeping. The words remain in your book on every page at once and last for a few hours. Only you can see the words. The book can send and receive messages from any plane, but while on Mechanus, messages written in other books will appear in yours immediately.

When the book is opened with intent to cast a spell as described in the spellcasting feature, a random short passage is pulled from the books' collective history and displayed. After the spell is cast, or if the book is closed, the message immediately disappears. This message only appears in your book.

Destroying the Book The books are nearly indestructible, and their magic very difficult to interfere with. First, the book's link must be severed from the others. In order to sever a book's link, it must be kept under dampening magic for 10d10 consecutive days, during which time it features cease to function. Dampening spells include hallow, imprisonment, non-detection, and Nystul's magic aura. Note that if brought into contact with another Book of Dispater, or if brought to any layer of the Abyss for 24 hours, the severed book will reestablish its link. Once the link has been severed, the book must be repurposed to render the magic permanently inert. There is no strict measure for such a task, but writing a novel within its pages, turning it into a manual or guide, or filing it with drawings and sketches will be enough to turn the book completely mundane.