Dungeon

Dungeons are self-contained dimensions created by the source. They appear as small, independent worlds, inhabited by monsters and various flora and fauna that are sometimes magical in nature.

Layout
The physical existence of dungeons consists of two main parts: the dungeon gate, and the dungeon interior. Of these, colloquial usage of "dungeon" generally refers to the dungeon interior.

Dungeon gate
Dungeon gates are large rectangular portals through which one can travel between the normal world and the dungeon interior. They appear as black voids with mana swirling around a central point, and are also surrounded in glowing wisps of mana.

In the novel, a dungeon's level of saturation can be determined from the shape of the dungeon gate and "mana distribution"; this implies that the shape of a dungeon gate is not fixed. It's unclear what mana distribution means. However, this may refer to the color and shape of the mana surrounding a dungeon gate. In the webtoon, these are indeed portrayed as fluctuating with the saturation level of the dungeon. A normal dungeon at low saturation has a gate with blue-tinted mana swirling normally, while a saturated dungeon about to burst has a gate with red-tinted mana taking more jagged, electric shapes.

In the real world, gates are present across Earth, generally floating a few feet above the ground. What they consider "ground" for this purpose can vary from actual roads and earth to the roof of a skyscraper. The gate is similarly positioned on the inside of the dungeon. Once a gate has been activated by someone trying to enter a dungeon, the portal remains open for an hour, after which it closes and goes into an inactive state. Though it does not physically disappear from either the real world or the dungeon interior, passage through it becomes impossible. This inactive state is maintained until the dungeon has been cleared, or until all those who entered from Earth are killed. It's also possible, in case of an emergency, to force a dungeon gate open from the interior by using a Gate Stone near this entrance gate.

When a dungeon has successfully been cleared, another gate appears where the boss monster for that dungeon was originally positioned. This exit gate is linked to the same Earth portal as the entrance gate, and allows Hunters raiding a dungeon to leave without having to travel all the way back to the entrance. This exit gate presumably persists until all raiding party members leave the dungeon.

Dungeon interior
The insides of dungeons are alternate dimensions, not located anywhere on Earth. They can be open-air landscapes, with what appears to be a sun in the sky; again, as dungeon gates transport people to alternate dimensions altogether and not to different locations on Earth, this is likely not the solar system's own Sun.

The landscapes found inside dungeons vary wildly. Dungeons can have different terrain, including (but not limited to) slime, seashore, rocky, or volcanic. As discovered by the research team Dungeon Persons, it's possible to partially identify the characteristics of a dungeon's interior based on various factors including the time of its formation, its surrounding real-world environment, general geographic location, and so on. This identification requires a calculation process complex enough that it can't be easily memorized.

Dungeons vary in size based on their rank, with higher-rank dungeons being spread out over large distances that can take days to cover. Some dungeons (generally high-ranked ones) are even spread out across multiple "floors", with floor-level boss monsters having to be killed in order to proceed to the next floor. Upon killing floor bosses, a portal similar to the exit gate appears to take a raiding party to the next floor. As with exit gates, there doesn't appear to be a time limit on crossing through the floor gate.

Though dungeons are often natural landscapes, they occasionally contain ruins, such as collapsed cities, indicating the former presence of some sort of society. None of these ruins have any writing or remains recognizable to humans.

Creation and placement
Certain laws govern the formation and placement of dungeons, such as the population density in the surrounding area; more dungeons appear in areas with higher population density. These laws were studied by Dungeon Persons, which was eventually able to refine and reverse-engineer them to a degree of precision such that the appearance of dungeons could be predicted in advance (though this information was kept secret by the United States). The calculation process for this is likely to be just as complex as that predicting the interiors of dungeons, if not more.

Dungeons are described as being "constructed" spaces. As with items, though they appear identical to regular physical locations, they are created through arrangements of mana. Standard dungeons made by the source have highly complex mana arrangements, while custom dungeons created by the transcendents (such as Newcomer's dungeon) have simpler structures. The mana structures underlying dungeons can be tampered with, generally by individuals who are able to identify and make similar adjustments, as for items. Earlier theorizing suggests that dungeons, particularly those containing unidentifiable ruins, are recreated from the remnants of worlds devoured by the source.

Ranks
Dungeons generally range from F-rank to S-rank. The rank of a dungeon determines its general difficulty, as well as the strength of the monsters that appear inside it. This rank can be detected from the outside of the dungeon, presumably by somehow measuring the mana levels of the dungeon gate.

Dungeons are also further classified by grade in addition to ranks. A high-grade dungeon of a particular letter rank will be more difficult than a low-grade dungeon of the same rank. High-grade dungeons of a particular rank are presumably close in difficulty to the low-grade dungeons of the next rank up.

Inhabitants
Dungeons are inhabited by various flora and fauna, not all of which are magical in nature (though they are generally not found on Earth). Landscapes are covered largely in non-magical trees and plants, if any, and magical trees and animals are scattered throughout.

Monsters
The most relevant of a dungeon's magical animals, as well as the occasional magical plant species, are classified as monsters; these serve as the targets for Hunters raiding dungeons. Dungeons always include a variety of standard or "mob" monsters, as well as one or more monsters that are visibly far stronger than the mobs, known as the boss monsters.

The types of flora and fauna that appear inside specific dungeons generally depend on the environment and rank of the dungeon; for example, the flame-attribute Horned Flame Lions appear inside a volcanic dungeon. It's possible, although vanishingly rare, for monsters that don't match a dungeon's rank or general attributes to appear inside them. On occasions where a monster equal or greater in strength than the original boss monster appears, they can kill the original boss and replace them as the dungeon's boss.

More monsters spawn inside dungeons as time passes. The number of monsters compared to the overall capacity of the dungeon is referred to as the saturation of the dungeon. At low saturation levels, dungeons have fewer monsters, while at high saturation levels, dungeons have many monsters. When saturation levels grow too high, monsters begin spilling over to the outside of the dungeon, resulting in a dungeon break. By periodically entering and culling the monsters to keep them at manageable levels, dungeon breaks can be minimized.

Byproducts
TBD

Raids and management
Dungeons can be raided by appropriately-ranked teams. To clear a dungeon and have the raid count as completed, the raiding party only needs to kill over half of the mob monsters as well as the boss monster(s) of the dungeon. (It's recommended, however, that the party kill as many mob monsters as possible, since the more monsters are killed, the longer the dungeon will remain stable afterwards.) Upon completing a raid, the raiding party is granted raid completion rewards. Rewards for the first raid on a dungeon are better than those for subsequent raids, and higher-ranked dungeons give better rewards than lower-ranked ones.

Dungeon management rights can be bid on by guilds or raiding teams, granting that guild/team full control over when raids are conducted and who can access the dungeon. When a dungeon first appears, if it's close to a break, the Hunter Association of the country it's located in gathers a team for an urgent raid. However, if it's relatively unsaturated, the dungeon management rights are put up for auction. The first group to raid a dungeon gets priority when bidding for its rights.

Raiding parties attacking individual dungeons can create strategies for raids that are made public to all those interested in the dungeon.