Creating a catalogue of Mythos tomes

It is often said that every one of us has a good book inside us. Unfortunately, given the nature of some of the texts listed in this collection, this idiom may end up being more literal than desired. From memetic graffiti and maps of non-existent streets, to the wisdom of the Cats of Ulthar and a forbidden text written on the skin of the last reader, this supplement is a catalogue of the weird, powerful, and downright dangerous tomes of eldritch lore that are housed in the script library of the Miskatonic Playhouse.

From the Library of the Playhouse started life in September 2025 as a competition run by Hedge on the Chaosium discord server for Impromptu Con 2025. Entrants were encouraged to create their own Mythos tomes, and while not eligible to enter the team of the Playhouse were inspired to write their own. Setting ourselves a deadline of Halloween ‘25, our initial plan to produce a small pamphlet with a handful of entries soon expanded into a full blown sourcebook with over 60 tomes, as well as details on how to create your own tomes, with random tables to roll against. We even included an original short horror story, entitled Ex Libris to act as a chapter break.

We were grateful to receive contributions from SR Sellens, Lynne Hardy, Keris McDonald, T A Newman, John Hedge, Pete Burgess, Steve Anderson, Lydia Malings, Jayson Green, The Cosmic Outpost, Matt Crouch, and Rick Boost.

This supplement, available on DriveThruRPG contains:

• 66 original Tomes of Eldritch Lore with detailed descriptions, with dates ranging from the beginning to the universe to the end of days;

• New spells, effects, and monsters linked inextricably with some of these forbidden books;

• An original short story illustrating the dangers of such texts;

• An appendix detailing how to create your own tomes, with random tables to roll against;

• A print friendly/text only version.