Magic in Masks – Tomes & Spells


The length and scope of MoN allow Keepers and Investigators to dig deep into magical resources and practical applications that may not often be available in shorter campaigns and brief scenarios. As many players will begin CoC games with Mythos-naive PCs it will take time for them to acquire knowledge, as well as the necessary artifacts and tomes to practice magic. In MoN, they will brush up against some of the most prestigious grimoires available in the setting and have the opportunity to study these incredible and world-shattering texts. To maximize the value of spells and tomes for your campaign, you may want to tweak some of the rules for everyone’s benefit. There are over twenty potential tomes listed in the campaign book for your Investigators to discover and with them an outstanding array of spells. Familiarizing yourself with the texts and their associated spells can help heighten their utility for you and the players. We’ll provide some spell references at the end of this article that you may like to refer to during the campaign.


In MoN, tomes range from thin books of poetry sheathed in hunting horror skin (Amongst the Stones) to legendary, ultra-rare works like the Book of Eibon and the Necronomicon. Any one of these books should hold some value for your players, either as a source of clues, Mythos knowledge, or spells (along with their accompanying Sanity Loss, of course). We find that a combination of all three provides our players with the greatest satisfaction. The Masks Companion offered an outstanding reference for tomes, but the latest MoN edition altered some of the tomes provided, so, over time, we will be providing a separate article covering each tome, where we may draw inspiration from the Companion, as well as other Mythos works, to provide some useful campaign connections and backstory. This will allow you to reward your players with some details discovered in their research and study. They may have paid dearly to acquire these tomes, and by using the item to enrich the game, you help offset the group’s loss.

The simplest mechanic for extracting value from the Mythos Tomes is by reading and studying them. While the rules may be easy and clear, the process of studying a Mythos tome can be cumbersome for Investigators, particularly when we are talking about works with a study time well over a year (Pnakotic Manuscripts, Necronomicon). We would like to offer some suggestions to streamline the process for your players and eliminate some potential roadblocks. 

Deciphering tomes can be quite challenging, but Keeper’s may expedite the process.

All tome study will begin with an Initial Reading (or Skim). You will be presented with a certain amount of flexibility in how long this first pass reading may take for Investigators. An option we have employed in our campaigns is to allow Investigators to skim a book during a single day of travel. This allows several investigators to study the text and learn a variety of facts and spells based on their interests. You could extend the length of time for reading during active campaign sessions, such as returning to your room each night in London, to review the Liber Ivonis you found in the Penhew Foundation basement. After a predetermined number of dedicated study evenings, your Investigator will have completed the Skim

Attempting to decipher demonic puzzles could result in unexpected visitors.

You may also choose to eliminate Language reading rolls for Initial Readings based on the age of the text (Keeper Rulebook p.174) so that your players need not waste valuable study time due to failed rolls, particularly if you chose to lengthen the Skim time. Alternatively, you could lengthen the time of study for failed language rolls, and even reward speedier examinations with Hard and Extreme successes. For example, an Extreme success during a skim could not only provide the Mythos skill gain but potentially reveal a spell of Keeper’s choice. If you are calling for language rolls, you can potentially employ some dangerous consequences for failed pushes, such as accidentally casting a Contact Nyarlathotep spell or summoning a mythos monster to their room at the Hotel Savoy.

To maintain an exciting campaign pace, you may want to consider altering the duration required for Full Study (or Thorough Reading). A simple rule of thumb may be to require a full inter-chapter voyage to complete Thorough Reading of a text and acquire the associated Cthulhu Mythos gains. The lengths of voyages will vary, and you may want to alter this at your discretion. Full Study of the Goddess of the Black Fan (2 weeks) or Africa’s Dark Sects (6 weeks) should certainly take less time than the R’lyeh Commentaries (54 weeks). If your players wish to use the tome as a reference book, you may wish to consider whether or not you will require a Full Study to do so. On the other hand, putting a pause on the campaign so your players can undertake deep study and learn spells in relatively safe locations can help you run down the calendar to put the campaign finish time closer to the 1926 eclipse. 


Once a book has undergone the initial reading, the Investigators should now have access to spells. It remains up to you to determine the length of time required to learn a spell, and whether or not you simply wish to provide your player with a full list or select a few interesting spells. The campaign book provides alternative names for spells to somewhat obfuscate their rulebook correlate, but you may like to take it a step further by providing a passage or brief description of the effects. Learning a spell could even be an accidental effect of further study, rather than a focused effort. 

Investigators may all wish to learn spells or dedicate one team member to the task.

The Keeper Rulebook suggests 2D6 weeks as the typical time required to learn a spell. Again, we like to apply the inter-chapter voyage as an opportunity for players to learn a spell or two depending on voyage length. You may elect to require INT rolls for players to learn spells. The rules set the INT difficulty at Hard to successfully learn the spell. You may choose to alter this based on your campaign, timing, Investigator Cthulhu Mythos skill, and prior experience learning spells. If your player group prefers to have a dedicated spellcaster, you may want to modify their study and success requirements. You may find it interesting to encourage specialization with spells by rewarding bonus dice or certain spells to players based on their interests. As with tome study, any failed pushes should have fun consequences for Investigators and anyone unlucky enough to be nearby. 

Investigators collaborating with interdimensional horrors may find themselves on a slippery slope.

Players may also learn spells from NPCs, including allies such as Dr. Ali Kafour (p.374) and Old Bundari (p. 440). Depending on the nature of the relationships players could conceivably learn spells from Edward Gavigan (p. 288), Zahra Shafik (p.288), and Ssathasaa (p.226) in London. You may require a predetermined length of type for tutelage or require 1D8 days for the process. Finally, your players could learn spells from Mythos entities. This could manifest as insertion of knowledge within the Investigator’s mind via a dream, telepathy, or a vision, including episodes due to the Mask of Hayama. It could simply come in the form of a gift from a Mythos being. Perhaps Nyarlathotep sows confusion and chaos by providing a particularly dangerous or disruptive spell. Maybe Nodens reaches out to an Investigator to supply a critical spell they missed. In the event a deity tampers with an Investigator’s mind, you should strongly consider levying a sanity tax in exchange for the spell. Remember you may want to require an INT roll to retain the spell, either after initial transmission or first casting. 

Given the variety of Mythos tomes available to your Investigators, they will have access to a range of spells; however, some spells play a much more substantial role in the campaign than others. A good number of the spells may have little practical use for your players as they probably will not have a strong urge to Facetime with Cyaegha (I fully expect to be wrong about this, though). We have broken the tome and spells into what we find to be useful references. Feel free to duplicate and modify as you see fit (Google Sheets Link)

Tomes – Useful Information

Tomes – Spells

Tomes – Summon & Contact

The many tomes available in this campaign should be exciting loot allowing your players to open up a big dangerous magical toy box to add some eldritch flavor, useful player tools, and memorable events to this adventure. 

By the end of your campaign, the Investigators may have amassed an impressive Mythos tome library. Or collapsed into abyssal madness.

4 thoughts on “Magic in Masks – Tomes & Spells

  1. Paul says:

    Very nice article! I’ve noticed that some of the google sheet entries about tome references had asterisks or were outlined in yellow. Is there any meaning to that?

    1. Keeper Doc says:

      Great question! Apologies for leaving that information out. The boxes highlighted yellow contain spells potentially (or definitely) important to the campaign. The campaign-impacting spells are noted with an asterisk. I’ll update the post to reflect that.

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