Chthonicism is the generally accepted name for the faith of the Tenebrous Church. The Church calls its members “Faithful” but “Chthonics” and “Divers” are also common names. The symbol of the faith is a Black Flame, usually carved from obsidian or made of anodized black steel. Often left purposefully sharp along one edge of the flame to be used as a cutting tool. The Black Flame said to symbolize the God in the Deep, a fire which casts no light but may burn the world.

Tenebrous ChurchEdit

The most powerful single human institution. Though not directly in the lead of many nations and cities, its faith connects and drives about 80% of humanity. When it proclaims things, the whole of humanity listens and the great majority obey. It is spread throughout the world of humanity but its leadership and greatest concentration of power is in Empyrean, the great inverted cathedral city known for its obsidian and basalt construction, Built in highly volcanic area with a great deal of chemotrophic flora and fauna.

The faith focuses on how humanity ended up underground due to its nature and how salvation comes from descent closer to god, who lies somewhere deep in the earth. The holy book contains many moralistic stories which teach not only tenets of what constitutes a good person but also techniques for caving.

The church has a complex organization, with many layers, leading up the Stygian Council. Layers organized towards depth and exploration, with Acolytes called “Aspirants”, Priests known as “Guides”, church leaders as “Delvers”, and leaders of a local group of churches as “Masters”. Above masters the organization goes through “Lightless”, “Abyssal”, “Chthonics” and “Stygian”. Advancing in the church requires taking pilgrimages into the deep, with those at its height said to be those who have gone the very deepest and returned alive and sane. Many are said to be living saints. 

They make the most commonly used coins in human territory. Called the Fathom, they are retangular with a lip around the edge. The lip is grooved such that the coins can interlock and stack front to back quite securely. They come in different denominations which are of slightly different sizes (Larger as they gain in value) with different engravings.

The Black BookEdit

The book associated with the faith is what the Church calls the “Book of Truth” but also called “Chthonic Codex” and “Black book”, due to its black outside and black pages with faintly glowing white ink. Known for being able to be read clearly in absolute darkness and in light. Reproductions of part or all of the book are common, but actual editions of the book are less common, usually only found among Aspirants and higher levels of the church.

The Book follows a “Depth” model, with each chapter called a “Strata” and with the very basic information in the first chapters and more detailed, complex or esoteric information hidden in other chapters further on. The book is half a religious text, half underground exploration and survival manual, though often somewhat obfuscated with story and metaphor.

The Chronic PilgrimageEdit

A central precept or concept of the church is that of the Chronic Pilgrimage. The idea is that god and divinity lie deeper within the Earth.  Those that make the pilgrimage deeper within, particularly those doing it on foot instead of in Bores or the like, are therefore seen as more holy or have a greater connection/understanding of God.

Because of the Pilgrimage is so important in the religion, those exploring the depths for reasons unrelated to faith hold an odd place in the public mindset. The hard line believers hate them because they see such actions as desecration of holy ground for mundane purposes. The more accepting hope, often with some degree of infuriating smugness, that the explorers will find their way to god. The majority of people are usually indifferent with a few romantics who really like them. The Church generally accepts explorers though they don’t count their explorations as pilgrimages and are quick to force them to sell anything of value they want. Objects from Tombs and Antediluvian creations are foremost in that category.


Saints are those who have gone deep enough into the earth to experience the divine and return changed. There are Living Saints, Saints (general name for a human who died after experiencing the divine, either as a result of it or later), and Feretrar (Blessed shrine keepers of the Antediluvian race).  Saints are beloved and worshipped as part of the Tenebrous Church, though living saints are usually carefully tracked and their bodies are taken upon death.

Saints sometimes go mad in response repeated exposure to the divine or if they are exposed too much in one go.  These Divine Fools are powerful and dangerous, usually wandering mad through the caverns.


Antediluvians are enormous humanoids of extremely varied shapes. They often have proportions that seem wrong to humans, such as limbs that are too long, asymmetrical arrangements, excessive or distressingly minimal muscle mass, and so forth. They have a variety of skin colors, including deep reds and blues, metallic copper, silver, gold, and semitransparent crystalline. Their eyes are solid black, their bodies hairless, and their faces are usually semi-human but completely lack a nose and their mouths are often oversized and gaping.

They are extremely resilient, powerful, and ignore injury as much as is physically possible. They are usually 9-10 feet tall, and their movements are odd. They often seem dazed or machine like, only to jerk into rapid motion and then suddenly hault again. It's as though they don’t really know how to work their bodies, like a teen driver struggling to control a car. They are indifferent to hostile when it comes to encounters with others.

The Church preaches that the Antediluvians are the remnants of a race which inhabited the world before humans; that the Antediluvians serve god’s desires. The Church says that the Antediluvians, along with a few other forms of life, were spared the destruction of the surface when God first walked in anger upon the Earth. The Church says they were saved because they were without sin. The Antediluvians serve now as builders and caretakers of tombs and shrines. At least they are known as Tombs and Shrines but their actual use is unknown. They also decorate Messenger paths, fight back against any escaped Entombed, and generally act as the army of God.

Messengers are beings which the church proclaims are created by God to perform a purpose. Messengers take various shapes but they are all absurdly powerful and dangerous; they melt tunnels straight through solid stone  in long, curving paths. Antediluvians quickly come in to decorate these tunnels and build branching complexes of tombs and shrines off of them.

The Entombed are beings that are sometimes found imprisoned within areas of Antediluvian make. They are entombed in burial chambers known as Cists (not misspelled)  though the are known to break free and stalk closed off Antediluvian areas or create burrows of their own. The Church claims they are traitorous beings or mistakes, failed divine beings or something tossed away by God. The Cists often contain divine materials and Relics, as the Entombed are either buried with them or seek out and horde them. The Entombed themselves often contain usable divine parts.


Diving is directly connected to the church; though not all who use diving are connected to the church, the church is the leading authority on it and has many experts and old hand users of it. They connect it to God in a vague way, either as an extension of God or as traveling into some sort of planes of God’s creation.

Diving plays a large part in the Chthonic religion, both as part of the faith and a major reason why they are such a powerful organization in the underground. It allows them not only to wield potent arcane powers but is also a major proof that their faith is correct.  It's hard to doubt holy men who pull miracles out of thin air.

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