Using This Content

This part of the site provides rules for both players and game masters (GMs) to incorporate elements of the venerable Cthulhu Mythos into their Pathfinder Roleplaying Game. Here, you will find tips on how to run fantasy horror games, rules for new playable races, options to customize player characters' class features for cosmic horror games, new rules for dread and insanity in the cosmic horror tradition, new spells and a new ritual magic system, new items and artifacts, and more. Players will find the most use in the races, class options, dread and insanity rules, spells, and items (with the exception of some spells, rituals, and items linked directly to Great Old Ones and Outer Gods).

Other options include new feats and a new skill, Profession (Yog-Sothothery philosopher), which can be used for most matters covered in this part of the site but strains the sanity of those who delve into matters beyond normal mortal comprehension.

In the second part of the content, GMs will find rules on dread and insanity, new tools for challenging player characters, including descriptions of many dangerous cults and their tactics, rules for facing the overwhelming power of Great Old Ones and Outer Gods directly, and dozens of horrific monsters, including many new interpretations of Mythos monsters previously published for the Pathfinder Roleplaying Game system. All of these rules are generally useful for building antagonists in any campaign, but they are especially appropriate for one that involves the Mythos to some degree.

All of the rules in this part of the site can be used with just the Pathfinder Roleplaying Game Core Rulebook and Pathfinder Roleplaying Game Bestiary, but a few optional elements are provided for groups using a wider variety of Pathfinder Roleplaying Game books. In some cases, where our new foes and rules were best captured by material printed in other Pathfinder Roleplaying Game books (such as Great Old Ones offering the Void domain or Father Dagon's tsunami spell-like ability), we reprinted those rules in the appropriate section for ease of use. This reprinted text clearly indicates the source it came from.

Content Priority

Content in this section of the site refers primarily to other content in this section. For example, any reference to rituals refers only to Mythos Rituals, while any references to creatures probably involve the Mythos Bestiary. If - and only if - the content is not present in this section should you look elsewhere (generally the official bestiaries, or a quick online reference at

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