If one were to take a look at the ground beneath their feet, they would surely conclude that the foundation of the world is a solid and unyielding thing. An impression that would only grow stronger if they tried to dig deep into the earth and stone, for most of our planet is indeed composed out of hard, solid material.

And yet, this initial impression would be mistaken. Beneath the surface of our planet, there lies a vast network of caves and tunnels that extend into seemingly every corner of the planet. Some places contain denser concentration of the caves and tunnels than others, but no one has ever found a land that was entirely free of them. People call it the Underworld, the Dungeon, the Labyrinth, and countless other names. It connects to the surface world though openings both large and small, and it descends into unfathomable depths below, creating a habitat full of dangers and wonders beneath our feet.

The Dungeon had captivated humanity since the beginning of recorded history. It is the source of magic. It is the birth place of monsters. It contains inconceivable wealth and cosmic secrets. A thousand expeditions had been launched into its depths – to plunder it, pacify it, make sense of it, or simply try and reach its bottom. Many of these had disappeared without a trace, never to be heard from again. Many more had returned with little to show for it. And no one had ever found a bottom. The interest never waned, however, and where there is a will there is a way.

This document is designed to give the reader some basic facts about the topic and dispel common misconceptions about the Dungeon. It is my hope that it will spark interest in the reader about this part of our world, which is so influential in how we live our lives and yet is so often taken for granted.

The Dungeon and Mana:

Probably the most obvious trait of the Dungeon is the relationship it has with ambient mana. The Dungeon is very rich in ambient mana, and the deeper one goes the higher the concentration of ambient mana becomes. This effect doesn’t appear to ever actually stop. No matter how deep one descends, the levels of ambient mana keep growing. It is rumored that if someone goes deep enough, the levels of ambient mana become high enough to passively induce mana poisoning in human beings, regardless of whether they try to draw in ambient mana into themselves or not. Reports relating to such deep expeditions are often highly confidential, however, so confirmation is hard to find.

Ambient mana in the Dungeon is rarely static – instead, it flows from some unreachable place deep underground and gradually rises towards the surface, thinning out as it is absorbed by the walls of the tunnels and the life forms that make their home in them. The bigger and straighter the tunnels, the less mana is lost during its flow towards the surface. This can create localized areas of atypically high ambient mana density, if a large vertical shaft connects a deeper portion of the Dungeon with areas near the surface.

This flow of mana is also usually accompanied by air currents that keep dungeon air from growing too stale and make the entire underworld far more livable than it would otherwise be. Since air is constantly moving upward from the Dungeon depths but never runs out, there is presumably a source of it somewhere in the depths. This source, much like the source of ambient mana itself, has never been found.

The Dungeon is connected to the surface in many places. These kinds of Dungeon openings are very easy to detect, because they invariably raise the ambient mana levels on the surface by their very presence. Even shallow portions of the Dungeon have significantly higher levels of ambient mana than most areas on the surface, so a Dungeon opening constantly spewing plumes of mana-infused air into the area is bound to raise its mana levels. Places where the Dungeon connects to the surface like this are called mana wells.

In fact, it is widely believed by mages that all ambient mana ultimately originates from the Dungeon. The main proof for this is that if one compares the map of known mana wells with a map of ambient mana levels, it immediately becomes obvious they match almost perfectly to one another. In the rare few cases where a high level of ambient mana is not matched by an appropriately-sized mana well in the center of it, there are usually traces of a mana well that collapsed (or was forcibly closed) sometime in the past.

The Dungeon and Magical Creatures:

The Dungeon has plenty of inhabitants. One might think that the number of living beings would be highest near the surface and then gradually grow thinner and smaller as one descended into the depths, but this isn’t the case. Every corner of the Dungeon is teeming with life. It just gets progressively more powerful and alien the deeper one descends into the tunnels below.

All dungeon creatures are magical in some way. Mundane creatures sometimes colonize new mana wells before Dungeon denizens become aware of them, but they are inevitably outcompeted and driven out by magical creatures in time. After all, magical creatures can do everything a mundane creature can, but with additional advantage of magic on top, and the only limitation is that they need a certain level of ambient mana to survive. Since the ambient mana levels in the Dungeon are high, even in very shallow portions of it, they can support very powerful magical creatures that outclass mundane ones in every conceivable way.

The shallowest portions of the Dungeon – those closest to the surface – are often inhabited by magical creatures that are clearly based on mundane animals. This is where one may find things like fire-breathing beetles, hyper-agile bats, spear-like worms, and so on. Some of them may be very unusual animals, however. For instance, land dwelling octopuses that can masquerade as rocks and mushrooms, or a type of flightless bats twisted into a small humanoid form. Although dependent on high levels of ambient mana to survive, most of these creatures can survive on the surface for a brief period of time, and will sometimes raid the surface if they are desperate or driven from their homes by other threats.

Near mana wells, many magical creatures that live on the surface will adopt a hybrid lifestyle, moving freely between the surface and shallower levels of the Dungeon. Large mana wells may also have specialized species that rely on this kind of lifestyle and cannot survive without the presence of both in the area.

Finally, there are creatures that live in different area depending on the stage of their life. Some magical creatures live their initial stages on life on the surface, where there are fewer things to threaten them, but descend into the Dungeon when they grow older and the levels of ambient mana on the surface can no longer support their existence.

The biosphere of the surface layer is not uniform across the world, and in fact greatly varies from place to place. Due to the great number of bottlenecks in the local landscape, as well as other factors that are poorly understood, dungeon denizens are often localized inside their own small areas. Entering a brand new section of the Dungeon is always a dangerous undertaking, because one can never be certain what kind of creatures they would find there.

The shallow, surface layer of the Dungeon is the one more extensively explored and exploited by humanity. Although no part of the Dungeon can be said to be truly safe or totally understood, this level of the Dungeon is considered fairly accessible and even non-magical people feel confident making limited forays into it. Sections of it are routinely pacified and section off from the Dungeon as a whole to serve as storage spaces, dumping grounds, experimental chambers, mining areas, and so on.

There are a number of sapient races making their home in the shallow portions of the Dungeon, though none possess the technical or magical sophistication of humanity. Their relationships with humans are complex, but surprisingly peaceful. Though humans are interested in exploiting the Dungeon, they have no ambition to outright colonize this space and are wary of sending significant forces into subterranean tunnels. As such, unless Dungeon races raid human communities on the surface, most humans would prefer to leave them alone or engage in trade.

Deeper into the Dungeon, in what is known as the middle layer, creatures become more and more removed from the surface, both in terms of appearance and in terms of behavior. They never venture out into the surface unless some major disturbance has occurred, and would not survive there for long even if they are displaced there. Their appearance is difficult to place among standard classifications of life on the surface. Many of them are recognizably bestial in basic structure, but do not correspond to specific known animals. A middle layer denizen can be said to resemble a frog or a crab, but they are also clearly not those things when studied in detail. Vivisections often produce bizarre results, such as a weasel-like creature that entirely lacks a spine, a jellyfish being that contains a bizarrely human-like brain in its cap, or a mass of pink gel covered in eyes.

Middle layer is viewed with great fear and caution by humans, since even experienced mages could easily perish here. Dungeon denizens that make their home here are powerful and poorly studied. Information about specific species is scarce, and what little of it exists in publicly-available libraries is often useless outside of very specific sections of the middle layer. The middle layer, just like the surface one, often has a unique species and variants living in different sections of it. This means that anyone wishing to go there will be faced with a plethora of strange magical abilities that are difficult to plan and prepare for. Only an archmage, armed with a wide selection of spells and mastered magic types, can reliably take on an environment like this and emerge victorious. These people are in short supply, so forays into the middle layer are rare.

Some of the dungeon denizens on the second layer are confirmed to be sapient, but none of them seem to form large organized societies. Most of them are highly territorial and aggressive, and will not respond to human attempts at communication – they are only known to be sapient due to mind magic. The few species that are willing to communicate are difficult to talk to, as their understanding of the world is entirely alien to humans. These creatures have never left their tunnels, don’t live in civilized societies, and often make references to magical perceptions that not even mages can make sense of. They often perceive humans as both weak and stupid, and are not shy about letting them know that. No long-term trade or productive interaction has been accomplished between humanity and middle layer dungeon denizens.

What lies beyond the middle layer is shrouded in mystery. Past a certain point, the monsters become so dangerous that even the best human mages wouldn’t last long against them. Their appearance is utterly alien as well, and they can no longer be described as weird animals but instead assume utterly alien forms that rarely resemble anything familiar. Like literal monsters conjured out of speculative horror stories, these strange entities increasingly challenge one’s common sense as one delves deeper into the depths. There are rumors of beings that can exist in two different places simultaneously, creatures that can trap people inside their own private pocket dimension that they can conjure and dismantle at will, elephantine-sized predators that are totally soundless and invisible regardless of what detection magic one uses, and eel-like parasites that can phase straight through unprotected flesh so they can slowly feed on the person’s insides. Truth is hard to distinguish from fanciful tales when it comes to the Dungeon depths.

Fortunately for humans (and other surface dwellers), magical creatures that dwell in these depths are such massive mana hogs that they wouldn’t be able to survive more than an hour on the surface and would never willingly ascend that high.

Beliefs and Theories:

As stated, the Dungeon and its place in the world is a mystery. Humans have only scratched its surface and can hardly unravel its deepest mysteries at this point in time. The gods rarely gave a definitive answer about what it represents, and many of their explanations conflict with each other. That is not to say that there is a lack of theories and supposed divine wisdom preserved from before the Silence. Most cultures and religions have an explanation about the Dungeon, and many scholars have put forward various theories about the place. Until someone is able to actually reach its greatest depths and return alive, however, it is likely that it will all remain speculative.

As noted earlier in this document, something in the depths of the Dungeon is responsible for producing nearly all ambient mana in the world. Since the only other thing capable of producing mana is souls of living beings, many people believe there is something alive down there. Some people believe the world itself has a soul, which reside in the center of it. Others believe the creator god that fashioned the world sacrificed his own heart to bring life to the otherwise barren soil. One group thinks the gods built the world around the body of a sleeping giant, and that the world is doomed to ruin once he finally wakes up.

In Ikosian mythology, the dungeon is a remnant from the time the world was created, when the gods took the last Primordial Dragon and fashioned her body into the land we live in. The tunnels are dragon veins, and they all converge at the very center of the world. There, bound in divine chains but still very much aware and seething in hatred, lies the still-beating heart of the primordial dragon. This is the Heart of the World, or the Heart of the World Dragon, and is supposedly the source of all the ambient mana gushing upwards from the depths, as well as the source of monsters that stalk the tunnels.

Many people have raised doubts about this story. Unlike ancient Ikosians, we have a pretty good idea about how big our planet is, and it’s big. Very big. The amount of distance the tunnels would have to cover in order to reach the center of the planet is mind-boggling. Furthermore, some of the scientific theories are suggesting that a large portion of our planet’s interior is actually in a molten state – a giant mass of lava upon which the continents float, basically. That would seem incompatible with the idea that there are tunnels crisscrossing the entire planet all the way to the very center of it.

Many people have raised questions about how the Dungeon can even exist in its current state. They claim that natural forces should have collapsed most of the tunnel network by now, citing both scientific models and the observed rate at which human-controlled sections of the Dungeon deteriorate. The simple answer to this is that we don’t know how this works. Magic is the obvious answer, but no mage can identify the actual mechanism by which the Dungeon maintains itself. Sections of the Dungeon do collapse from time to time, but it is clear that the Dungeon is both far more resilient to structural damage than it should be, and that it has some kind of unknown mechanism for creating brand new sections to replace the destroyed ones.

There is a persistent rumor among delvers that there is a gigantic cavern somewhere deep beneath Altazia, forming what is effectively a small underground continent. Such a place has never been found, and it is unclear where the rumor originates from.

Origin of Dungeon Denizens:

There are two main theories in regards to where the monsters that inhabit the Dungeon come from: the hybrid theory and deep origin theory.

The hybrid theory states that dungeon denizens come both from the surface world and the unidentified depths below. The deeper, more alien creatures are said to have no relations to surface creatures. They originate from the bottom of the Dungeon, whatever it is, and have gradually extended their influence upwards. The inhabitants of the shallow and middle layer, however, are clearly just magical animals. They are surface creatures that have colonized the Dungeon and gradually developed magical powers due to long exposure to mana. At certain depths, these two ecologies meet, though the exact point at which this happens is in dispute. The hybrid theory is currently the more popular of the two theories.

The deep origin theory states that all dungeon denizens originate from the depths of the dungeon. The more animal-like creatures in the surface layers of the dungeon are just monsters that learned to mimic the creations of the gods to better infiltrate the surface and lure the unwary into a false sense of security. This was once the more popular of the two theories, but it has fallen in disrepute in recent times, since greater exposure to the surface dungeon denizens has shown that these creatures just aren’t that hateful and duplicitous. They’re most just vicious animals with magical powers. The spread of magic and firearms has also made dungeon denizen raids on the surface a much rarer thing than it was in the past, which makes people a lot less negative about the place.

Dungeon Journeys:

One question that is often asked is whether travel through the Dungeon can be used to circumvent surface obstacles. The answer is yes, but with some caveats.

Surface sections of the Dungeon are often poorly connected to each other. Thus, if one wants to travel large distances through the dungeon, then at the very least they need to descend into the middle layer from time to time. This means that any person or group that wishes to travel through the dungeon must be uncommonly powerful and experienced. Because large sections of the Dungeon are poorly mapped and many dungeon denizens are fond of ambushes, progress is bound to be slow. If speed is desired, traversing large stretches of the Dungeon is a poor choice of action. Finally, although the Dungeon is teeming with life, very few of it is safe to eat by human beings. Dungeon denizens, especially ones from the deeper reaches, have highly magical flesh that has strange, usually negative effects on human that eat it. Thus, you will have to ensure a steady supply of edible food throughout the journey.

Finally, a question of whether it’s possible to travel beneath the ocean to another continent through the Dungeon is sometimes raised. Such a feat would require one to descent into the deep dungeon and stay there for a long time, which is suicide for just about anyone. No one has been reported to have even attempted it, much less succeeded.