(aka Liber Paginarum Fulvarum) A powerful book of magic
in the library of Unseen University
, written by Achmed the Mad
(aka Achmed the I Just Get These Headaches).
It's a phonebook that tells how to call to the dead.
A wizard started to read the Necrotelicomnicon and let his mind wander. The next morning they found all his clothes on the chair with his hat on top of them and the book had a lot more pages...