|Pic: Wellcome Images|
Mysterious, ancient, tomes of magic are the cornerstones of many a great adventure, and the other day I came across mention of one that was new to me: Clavis Inferni aka The Key To Hell.
This is crying out to be the focus of a Call of Cthulhu scenario, or similar Lovecraftian horror tale, especially given that it is apparently penned in a code that has yet to be broken (much like The Voynich Manuscript).
The Blumhouse site has a tantalising introduction to this strange 18th Century tome, including wonderfully atmospheric speculation over its possible author (including "a Danish sorcerer so evil that he was cast out of hell by Satan himself").
It also includes a link to the Wellcome Images Library where pages from the indecipherable book of "black magic" can be seen in all their glory.