In his fiction, H.P. Lovecraft began to build a complex intermeshed web of weird-sounding extra-dimensional, alien, and otherwise weird beings. He also invented obscure tomes of forbidden lore and nefarious cults of misguided worshippers. He also encouraged fellow horror writers to borrow his strange creations and add them into their own stories; in return, Lovecraft baked some of his friends’ alien names into his later stories.
In the century since this vast game of collective myth-building began, the so called “Cthulhu Mythos” — a name coined long after Lovecraft’s death in 1937 — has grown to become a patchwork of creations that is both expansive and problematic from an Intellectual Property perspective. While there are undeniably some parts of this Mythos that are firmly in the Public Domain, other parts have been added by more recent writers (some still alive) who retain IP rights to their creations.
When building a cool game scenario or campaign, the last thing anyone wants to be thinking about is whether the inclusion of this or that alien name might trigger a nasty email from lawyers representing a fiction author or the estate of a dead author. To make things easier for creators, the German Lovecraft Society invested an enormous amount of time and effort to isolate the “open” parts of the Mythos — effectively the elements invented by Lovecraft himself for stories that have now fallen into the Public Domain. They also built game statistics for those creations.
If you’re looking for familiar Lovecraftian horrors to add to your game or scenario … and you DON’T want to get bogged down in the legalities of which author/estate to contact about which odd-sounding god, creature, or tome … these are your go-to Mythos elements. We have taken the work by our esteemed German colleagues and partnered with them to translate them to English and tweak the statistics so they work with our Cthulhu Eternal and APOCTHULHU RPGs.
The Open Mythos is divided into Rituals, Artifacts, Tomes, Cults, and Unnatural Entities
IMPORTANT NOTE: THE OPEN-MYTHOS IS BEING PROGRESSIVELY TRANSLATED. ONLY A FRACTION OF THE FINAL CONTENT IS CURRENTLY IN PLACE ON THIS PAGE. IF YOU CLICK ON AN ENTRY AND FIND AN EMPTY DESCRIPTION, CHECK BACK LATER … THE FULL LIST WILL EVENTUALLY BE HERE.
The descriptions of the following rituals are, for the most part, directly based on rituals described by Lovecraft himself. They should serve as inspiration and orientation for the Game Moderator to design his or her own rituals.
This format for ritual description is as follows:
Study: study duration; SAN loss.
Activation: duration; WP cost; SAN Loss.
Description: The summary of the effect, necessary actions and prerequisites of a ritual. Sometimes the successful performance of a ritual also requires certain skill values. Sometimes the effect causes an increase in unnatural knowledge.
Ritual | Effect | Study | Activation |
Accelerated Healing | Heal another person’s physical injuries | days; 1d4 SAN | 2 turns; 1d4 WP, 1d6 SAN |
Aklo Sabaoth | Make contact with supernatural beings | weeks; 1d8 SAN | 1 hour; 1d8 WP, 1d10 SAN |
Annihilation | Torture and kill through pure mind power | months; 1d10 SAN | 1 turn; 1d8 WP, 1d10 SAN |
Banish Entity | Banish unnatural entities | weeks; 1d6 SAN | 1 hour; WP approximately 2 × POW of the entity to be banished, 1d10 SAN |
Body Swap | Take control another person’s body, transferring your mind into it | weeks; 1d6 SAN | 1 turn; 1d8 WP, 1d6 SAN |
DHO HNA Formula | View or travel to distant places | months; 1d8 SAN | minutes; variable WP depending on distance: 1d4 SAN (gaze, near) / 1d6 SAN (gaze, far) / 1d10 SAN (gaze, distant worlds); 1d4 SAN (gaze, earth) / 1d6 SAN (gaze to strange or mystical places) / 1d10 SAN (travel) |
Dominate Will | Take over will of another person for a short period | days; 1d4 SAN | 2 turns; 1d6 WP, 1d4 SAN |
Elder Sign | Protection against unnatural forces | hours; 1d6 SAN | 1 turn/1 hour; 10 WP per 10 m radius, 1d4 SAN |
Elixir of Life | Reanimate the recently dead | weeks; 1d6 SAN | 5 minutes; 1d10 WP, 1d8 SAN |
Erase Memories | Eliminate selected memories | weeks; 1d6 SAN | half hour; WP = SAN of victim, 1d6 SAN |
Essential Saltes | Raise the dead from their physical remains | weeks; 1d6 SAN | minutes; 1d8 WP, 1d10 SAN |
Forge Ancestral Bond | Create a mystic bond with a future descendant | weeks; 1d6 SAN | years; 1d4 WP and 1d4 SAN per repetition of the ritual |
Inflict Harm | Cause injury or illness | months; 1d8 SAN | 1 turn or minutes (depending on ritual variant); 1d6 WP, 1d10 SAN |
Music of the Spheres | An invocation to Azathoth | days; 1d4 SAN | 1 hour; 1d6 WP, 1d6 SAN + increase in unnatural knowledge by the same amount |
Open Dimensional Rift | Allows physical travel across vast expanses of dimensions, or through time | months; 1d8 SAN | 1 turn; 1d8 WP, 1d6 SAN |
Powder of Ibn-Ghazi | Briefly render invisible visible unnatural entities or objects visible | days; 1d4 SAN | 1 turn; 1d4 WP; 1 SAN |
Prolong Life | Prolong one’s life at the expense of others’ vitality | years; 1d6 SAN | one hour; 1d10 WP, 1d6 SAN (animal sacrifice)/1d10 SAN (human sacrifice) |
See Through The Ages | View the future or past of a person, object, or place | days; 1d4 SAN | 1 hour; 1d4 WP, 1d4 SAN |
Sign of Koth | Ward against the passing of unnatural entities | days; 1d4 SAN | hours; 1D6 WP and 1D4 SAN against a specific type of being or 2D6 WP and 1D6 SAN if potent against all types of Mythos creatures |
Summon Entities | Summon unnatural entities | days; 1d6 SAN | minutes to hours (approx. 2 to 3 × POW of entity in minutes); WP = POW of entity; 1d10 SAN |
Voorish Sign | Magical symbol of protection and knowledge | days; 1d4 SAN | 1 turn; 1d4 WP, 1 SAN |
Tales of cosmic horror often feature Items with inexplicable powers, including the ability to open doorways or unlock unnatural knowledge. When such Artifacts fall into the hands of player characters, they provide evidence of things that should not exist, since their unique properties are utterly impossible to explain with known scientific principles.
This format for describing an Unnatural Artifact is as follows:
Rituals: which Unnatural Rituals (from those described elsewhere on the Open Mythos pages) may be cast by using the Artifact.
Activation Cost: WP cost to activate the Artifact.
SAN Loss: The mental damage created through the use of the artifact to tap the forces of the unnatural.
Artifact | Rituals | Activation | SAN Loss |
Cthulhu Idol | Aklo Sabaoth (Cthulhu), Call of Cthulhu (see Entity stats for Great Cthulhu) | 1D6 WP | 1D10 to use the Sabaoth |
Golden Tiaras of the Deep Ones | Aklo Sabaoth (Dagon and Hydra), Summon Entities (Deep Ones). | 1D6 WP | 1D10 |
Great Race Mental Projection Apparatus | Open Dimensional Rift, Body Swap | 1D8 WP | 1D8 |
Jade Soul-Amulet | Summon Entity (Hound of Death) | 1D4 WP | None |
Mi-Go Brain Cylinder | None | 1D4 WP | 0/1D4 to use, 1D4/1D8 to travel |
Mi-Go Communication Implant | None | 1D4 WP | 1/1D6 |
The Shining Trapezohedron | DHO-HNA Formula, Summon Entity (Haunter of the Dark). | 1D4 WP or 1D10 WP | Up to 1D6 |
The Silver Key | DHO-HNA Formula (Dreamlands) | 1D4 WP | None |
TBD
Tome | Language | Study Time |
Azathoth and other Horrors | TBD | TBD |
Book of Azathoth | TBD | TBD |
Book of Dzyan | TBD | TBD |
Brick Cylinders of Kadatheron | TBD | TBD |
THE CTHULHU CULT (Armitage Files) | TBD | TBD |
Daemonolatreiae Libri III | TBD | TBD |
Ilarnek Papyri | TBD | TBD |
The King in Yellow (play) | TBD | TBD |
Liber Damnatus Damnationum | TBD | TBD |
The Nameless Book | TBD | TBD |
The Necronomicon | TBD | TBD |
Pnakotic Manuscripts | TBD | TBD |
The Scientific reports of Dr. Herbert West | TBD | TBD |
The Seven Cryptical Books of Hsan | TBD | TBD |
TBD
Cult | Description |
Cannibal Cult of Leng | TBD |
The Cthulhu Cult | TBD |
Cult of the Crawlers | TBD |
Cult of the Wise Ones | TBD |
Esoteric Order of Dagon | TBD |
Shepherds of Hastur (Cult of the Yellow Sign) | TBD |
Starry Wisdom Sect | TBD |
Witches Coven | TBD |
The descriptions of the following unnatural entities (races of creatures and unique beings) are, for the most part, directly based on horrors described by Lovecraft himself.
Two different formats are used to describe these entities — one for ultra-powerful “god-like” powers like Great Cthulhu or others of the Great Old Ones, and another for less powerful races of alien beings.
Entries for God-like powers described a minimum set of game parameters, since most encounters with such potent beings should be resolved in a narrative way rather than dictated by the whimsy of dice. To support a GM in weaving a compelling description of such a mind-blasting experience, a number of details are helpful:
The format for describing less powerful entities and races is more fully-featured in terms of game mechanics. It includes:
Entity | Description | Status | SAN to Witness |
Azathoth | Lord of All Things, Blind Nuclear Chaos, Idiot God | Outer God | 1D10/1D100 |
Beings of Ib | Faithful Children of Bokrug | Dreamlands Race | 1/1D6 |
Bholes | Destroyers of Worlds | Alien Race | 1D8/1D20 |
Bokrug | The Corruptor | Dreamlands God | 1D8/1D20 |
Cats of the Dreamlands | Graceful and Mysterious Denizens of Slumber | Dreamlands Race | 0/1 |
Colour Out Of Space | Incorporeal Devourer of Vitality | Alien Race or Entity | 1/1D6 (Extremely Small or Small), 1/1D8 (Medium), 1D4/1D10 (Large), 1D6/1D10 (Very Large), 1D8/1D20 (Extremely Large) |
Creeping Corpses | Animated Corpse-Colonies of Squirming Maggots | Product of Unnatural Rite | 1D8/1D20 |
Great Cthulhu | High Priest of the Great Old Ones | Great Old One | 1D10/1D100 |
Dagon and Hydra | Father and Mother of the Deep Ones | Powerful Deep One “Gods” | 1D10/1D20 |
Elder Things | Ancient Creators of Life | Alien Race | 1D4/1D10 |
Formless Hunter | Flying Terrors and Hunting-Horrors | Dimensional Horror | 1D4/1D10 |
Ghasts | Middle Predators of the Underworld | Dreamlands Race | 1/1D8 |
Ghouls | Immortal Eater of Corpses | Unnatural Race | 1/1D6 |
Gnorri | Grand Architects of Underwater Marvels | Dreamlands Race | 1/1D4 |
The God of the Sunken Temple | Nightmare Beneath the Waves | Great Old One? | 1D10/1D100 |
Great Race of Yith | Inquisitive Librarians and Temporal Meddlers | Alien/Temporal Race | 1D6/1D12 |
Gugs | Cursed Titans of the Stygian Darkness | Dreamlands Race | 1D6/1D12 |
Hastur | Possible face of the King in Yellow? | ??? | ??? |
Hounds of Death | Merciless undead hunters | Unnatural Race | 1/1D8 |
Hypnos | The Lord of Sleep | Great Old One | 1D10/1D20 |
Keziah Mason | Vicious Witch and Hideous Nightmare | Immortal Witch | 1/1D4 |
King in Yellow | Madness in Yellow Tatters | Great Old One | 1D10/1D100 |
Leng Folk | Semi-Human Merchants of Cruelty | Dreamlands Race | 1/1D6 (if undisguised) |
Mi-Go | The Fungi from Yuggoth | Alien Race | 1/1D8 |
Moon Beasts | Ruthless Slave Masters from the Dark Side of the Moon | Dreamlands Race | 1D4/1D10 |
Night-gaunts | Horror of the night | Dreamlands Race | 1/1D8 |
Nodens | Lord of the Great Abyss | Great Old One | 1D10/1D20 |
Nyarlathotep | Crawling Chaos and Messenger of the Old Gods | Outer God | 1D10/1D100 |
Polyp Horrors | Invisible and Semi-Substantial Masters of the Winds | Alien Race | 1D6/1D12 |
Rat Things | Brown Jenkins’ Kin | Changeling? | 1/1D4 |
Resurrected Abominations | Failed Attempts to Meddle With Life and Death | Mistaken Creation | 1D4/1D10 |
Resurrected Corpses | The Re-Animated | Of Sorcery or Mad Science | 1/1D6 |
Shantaks | Masters of the Skies | Servitor Race | 1D4/1D10 |
Shoggoths | Formless Horrors from Ancient Eons | Servitor Race (gone wild) | 1D8/1D20 |
Shub-Niggurath | The Black Goat of the Woods with a thousand young | Great Old One | 1D10/1D100 |
Spiders From Leng | Hunters on the desolate plains of Leng | Dreamlands Race | 1/1D8 |
Star Spawn | Dreaming Servants of the Great Old One | Alien Race | 1D8/1D20 |
Winged Servant | Space-borne Eldritch Horrors from Beyond | Servitor Race? Alien Race? | 1/1D8 |
Yog-Sothoth | The Key and The Gate | Outer God | 1D10/1D100 |
Zoogs | Inquisitive Forest Dwellers of the Dreamlands | Dreamlands Race | 0/1 |
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