Dungeons are literal manifestations of the otherworld into our native
reality. As a rule, dungeons subsume an existing building or construct, though
in rare cases it can spring from nothingness. Dungeons come in varying levels
denoting their 'oddness' level and the general lethality and power of the
aliens that dwell and multiply within.

All dungeons share one thing in common, they all posses a 'heart'. In the
center of the dungeon is some object, person, or idea, that keeps the dungeon
intact. When destroyed, killed, or deciphered, the dungeon reverts to its
normal terran form. This is usually the goal of MEC Dungeon Delving teams. A
Delve can take anywhere from an hour to days to over a week depending on the
size and complexity of the dungeon in question.

Normal people are warned to not approach dungeons and the entrance to
such places are marked clearly, cordoned off to prevent accidental victims. As
a rule, stronger dungeons ward themselves off with a layer of altered reality
and deadly creatures that keep all but the strongest away and keep the dungeon
from being undone.

Dungeons tend to come in 'themes'. One may be a twisted Victorian manor
filled with odd mobile puppets, grossly disfigured opulent humanoid guardians
and irritating but classy background music haunting the place. A graveyard may
become a crypt, filled to the brim with all manner of undead. Wraiths, ghouls
skeletons, in more powerful dungeons even liches and vampires. Places that
are unused or gathering places of intense emotion are more likely to be victim
to sudden transformation.

To make things all the more difficult, communication between the outside world
and those inside the dungeon are cut off. All forms of magical and mundane
long rage communication falter. The only exception to this is point of sight.
Some Dungeon Delvers have success in leaving behind a series of mirrors
and using them to piggyback messages. This isolation only stresses the need
of Dungeon Delvers to be dynamic and ready for all possible situations.

No matter how well equipped or trained, sometimes the Dungeon Delvers meet
defeat. The exact details of the loss are usually unimportant. None of the team
escapes if they've made an attempt at disarming the dungeon's heart and fail.
It's as if the dungeon itself grew malicious, and denies them any chance of
pulling out at that point. Such dungeons will often expand. Some say that it is
the dungeon feeding on its victims. Others postulate that it's a defensive reaction
to being threatened. Either way, it's a very real menace and the MEC tries to
send in squads that can diffuse the dungeon the first time around.