Background : Consider a typical dungeon, which has weak monsters at the top and the lower you go, the stronger the enemies become.

Some questions about dungeons have already been answered - why are they filled with puzzles, and how long it takes to repopulate them.

However my question is - what prevents the monsters from migrating to other floors in the dungeon? Some of the monsters that are on the lower floors in the dungeon are very powerful and crafty. What prevents them from just moving from like the 20th floor of the dungeon to the 10th, and becoming the boss of that floor ?

Or, the more general question, why do monsters remain in the dungeon ? They can probably figure out that going outside means they can hunt for food.

  • $\begingroup$ My answer to the linked question about population applies to this as well, it's all about why it's a dungeon $\endgroup$ – Separatrix Jun 24 '16 at 10:35
  • $\begingroup$ Magical world or non-magical? $\endgroup$ – Murphy Jun 24 '16 at 10:45
  • $\begingroup$ A typical world with dungeons for me is magical, so yes its magical. $\endgroup$ – King of Snakes Jun 24 '16 at 10:49
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    $\begingroup$ Because they don't fit through the door. $\endgroup$ – AmiralPatate Jun 24 '16 at 12:41
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    $\begingroup$ @AmiralPatate : Cant believe I forgot something so simple ;) $\endgroup$ – King of Snakes Jun 24 '16 at 14:20

11 Answers 11



One option is to make the stronger creatures deeply dependent on magic/manna and put a source at the bottom.

It seeps up through the dungeon.

The deeper you go the easier powerful magic becomes and the biggest, scariest and most powerful creatures need that manna to survive.

The creatures might want to leave but they need to stay for roughly the same reason that humans cluster around an oasis in the desert.

The less powerful creatures can survive further up and the least powerful can even survive on the surface. They may act as minions of the ones further down gathering supplies and food.

Indeed assuming that any creature has a certain Manna reserve and a certain manna requirement suggests a certain social structure such that the creatures on each level can temporarily project force against those a few levels above but would need to return to replenish their strength while those higher up are the ones which can't compete for the richer manna supplies lower down.

Some of the most powerful creatures would starve of magic on the surface and die but they can sit in their lair deep down coordinating attacks against the surface.

At very deep levels the rich manna field allows for highly magical plants, animals and materials to form/grow which even gives a reasonable incentive for humans to venture down. They get the chance to harvest magical plants and animals that only grow in rich manna-fields.

You might even have human outposts deep in a dungeon where magical crafting otherwise impossible can be done. If you want to make magical artifacts it makes sense to go to where there's lots and lots of magic available. These would of course suffer terrible attacks from the local creatures.

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    $\begingroup$ Good enough. I was thinking about an answer with slightly different angle, but it in the end amounts to the same, so I'll just one up yours instead of writing my own. $\endgroup$ – Ville Niemi Jun 24 '16 at 12:14
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    $\begingroup$ lol I love it... Kill a powerful creature? Kill too many creatures down below? And... there's less creatures soaking the manna and the creatures above get more powerful/reproduce faster. ... The crafters mighty find it worth a pretty penny to clear creatures below them so they can stay where they are and make more powerful stuff. Or other crafters might get angry because now the rats they've been easily fighting grow a few levels in strength. Could introduce some very interesting cross play as young adventures mess with the balance. $\endgroup$ – WernerCD Jun 24 '16 at 15:04
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    $\begingroup$ Manna: mystical food from heaven, from the Old Testament. Mana: magical energy. $\endgroup$ – Mason Wheeler Jun 24 '16 at 15:09
  • $\begingroup$ @MasonWheeler is there a version of Manna from hell? $\endgroup$ – Murphy Jun 24 '16 at 15:50
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    $\begingroup$ @Murphy Hellapeños $\endgroup$ – Mason Wheeler Jun 24 '16 at 15:50

First, just as executives tend to seek out the top floors of a building the the most powerful of entities likewise seem to gravitate to the lower, less accessible regions of a dungeon. Perhaps they just don't wish to be disturbed by every nuisance attempting to explore the area. Better things to do with time kind of argument.

Allowing the lesser or less ferocious creatures handle the "light work" or cannon fodder keeps one's self at full charge so to speak while hopefully wearing your enemies down. After all you have a reputation to maintain and underlings are just that underlings. If its serious I'll get involved.


  • $\begingroup$ Welcome to Worldbuilding Brent! $\endgroup$ – fi12 Jun 24 '16 at 15:10
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    $\begingroup$ This is also a good answer, Bosses wanting to keep their image :) $\endgroup$ – King of Snakes Jun 27 '16 at 7:05

In addition to Murphy's answer: depending on the monster type, they might be afraid of light and open spaces. That would stop them from getting away from the dungeon. Additionally, upper layers would not be "comfortable" for these monsters (as fresh air and a bit of sunlight comes through), thus they fight for lower floors which would also become status symbol. This results in stronger monsters in lower floors. Bosses could be monsters that decide to settle for an upper floor becoming the boss of that level. After all some of us chose to be big fish in small pond.

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    $\begingroup$ The lower you go, the more pressure... and the more heat... the rock above pushing down and the Liquid Hot Mag'a'ma reaching from below. Creatures use the heat to grow and the pressure makes them stronger/only lets the strongest survive. $\endgroup$ – WernerCD Jun 24 '16 at 15:10

There are several answers, but it depends on the dungeon and the monster.

Take, for example, the puzzles. Because no campaigns I know of start at the bottom of a dungeon, we can turn to reality. In tombs like the Egyptian pyramids and Chinese Emperor burial sites, the pallbearers, in order to keep the secrets of the traps, were trapped in themselves. This means that, logically, the traps work both ways. Therefore, monsters wouldn't push up of they were monsters more muscle than brain and couldn't figure the traps out.

The more intelligent could face physical barriers. For example, some are foiled by a locked door, no more. If they lack the faculties to break it down, then they cannot move on. Another possibility would be that moving up could cause harm- of they are susceptible to physical attacks, staying where they are could be safest, and they would be smart enough to realise it.

So that addresses the less intelligent monsters, but what about the bosses, intelligent and strong?

Bosses stay where they are because they have a purpose. Many times the bosses are set personally by the Dungeon Creator,and this understand why they should stay. Sometimes it is the creator itself. So, the boss knows why it needs to stay where it is.

Of course, this is all overlooking, one other thought- perhaps the monsters were spawned there. Let me frame it this way: if you were born in an opaque dome with no outside contact, and you were told that there was no outside, would you try to escape? No! So, it is possible that the monsters simply do not know that there are different floors to move to.

Overall, they could be unable to overcome a trap, or weak, or understanding of a purpose, or just kept on the dark.



Main idea of the French comic book series Dungeon, a donjon can actually a be a business built up to attract adventurers. They will bring their costly equipment, maybe win easily the first rooms, and then eventually die later, in other more dangerous places in the dungeon. The "Dungeon Master" will then hire the creatures and monsters as gladiators and give them a place or a treasure to keep. He will also take care of the inhabitants of the dungeon, feed them and manage the different species so they can live together.

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    $\begingroup$ So it's almost a kind of casino - each adventurer who enters is gambling, wagering his life and the equipment he brings along; after winning the first battle, does he "let it ride" by venturing further in, or "cash out" and leave? If he clears the first floor, he must then decide whether or not to "move to a table with a higher minimum bet" (descend to the next level), and so on. Every bet is essentially "all in" for the adventurer. (Edge case: adventurer narrowly escapes death, loses some gear in the process, leaves with less than he entered with.) $\endgroup$ – Dan Henderson Jul 5 '16 at 17:21

I have different answers for different kinds of monsters ...

Monsters fear human hordes or armies. The dragon doesn't fear a single mounted knight, even a knight with a magical +3 sword of dragon slaying. A regiment of crossbowmen and a bunch of ballistae, covered by a phalanx for close defense, now that is scary. For every one he fries, another steps forward. The vampire doesn't fear a single hero. A hundred villagers with torches and pitchforks are a different matter. A dozen villagers may fall, but sooner or later the tine of a pitchfork will find her heart.

So the clever monsters will go where average humans don't show up. Deep in the dungeon, beyond the bottomless pit and the spike trap.

The lower dungeon was tailor-made for the monsters. Dragons have an instinct to bring their hoard into a comfortable cave. So a dungeon builder who wants his pet dragon to defend his treasure vault would provide a dragons-only access to the lower levels (perhaps flying through the bottomless pit, see above) where a dragon can spread her wings. Can you imagine the size of a dragon tree? The upper levels are scaled for human minions.

A wingless and mindless dragon might find a cave with a trough for water and a trapdoor to provide regular meals. Perhaps the upper levels of the dungeon are damp, or in bad repair. The lower levels are nice and cozy.

So the big monsters can go to the upper levels. But they don't like it. They would fight those pesky adventurers at a disadvantage in the narrow tunnels. They could engage adventurers in the open, however.


[W]hy do monsters remain in the dungeon ?

Perhaps this is overally broad, and is obviously stated in different ways in other answers to this question, but the real reason breaks down to "Because it serves their purposes."

Any creature in any environment remains there because of the ecology.

[Note that for the following, I am assuming food needs are fairly well balanced. Lack of food may very well be a good cause for migration. Lack of migration but continued health indicates food requirements are being generally met.]

  • Food - whatever the creature naturally eats either is produced in the dungeon or comes to them, so there is no (or very little) need to go above ground. For our purposes, food includes water, etc.

  • Reproduction - The dungeons serves as an environment where creatures of the opposite sex dwell as well (a bit of a chicken and the egg problem).

  • Protection - Because a creature is powerful it does not mean it's invincible. Particularly, no animal would want to live under threat of siege either from third parties or others of it's own kind. Young, new or inexperienced creatures in particular are often vulnerable - killing a young dragon is much simpler than killing an adult dragon, slaying a lich is much easier if her phylactery isn't yet well hidden.

  • Hiding - While this could be protection as well, many of the creatures portrayed as living in dungeons are predatory. Predators have the instinct to hide not necessarily out of fear but because it makes their goals (preying on others) simpler if the prey has no knowledge of the predator.

  • Symbiosis - Creatures may rely on each other in some fashion (maybe those giant beetles really love that dragon poo =P).

  • Other Advantages - Bees build hives that have honeycomb. That particular structure has an advantage for the bees. While not necessarily made by the creature, there could be some advantages (such as treasure hiding already mentioned) that the creature finds advantageous in a dungeon. Likewise, a creature that is both light sensitive and needing a watery environment to survive would likely find a flooded dungeon a quite suitable habitat.

  • Free Will - If the creature is intelligent enough, perhaps it just likes being in a particular environment. Perhaps that dragon really does appreciate those hideous but tasty dwarfs' eye for decoration... perhaps that evil lich is pining away for the days of yore when she could torture others unmercifully and being in a creepy dungeon reminds her of the fear she used to see etched into the faces of her victims as they were dragged "below" to have unspeakable horrors visited upon them... who knows?

And finally, while not ecological in nature, the monster could of course be forced to live in that environment by external forces (that is the only place it can do/find xyz, despite its wishes to do otherwise, or is otherwise trapped via circumstance e.g. by accident, inability to leave (doors!), magic or hostile "others").

[W]hat prevents the monsters from migrating to other floors in the dungeon?

With the exception of reproduction (as defined in the list above), one or more of these reasons could apply. While many dungeons are generic, real life would suggest that floor 10 would not necessarily meet the needs of the creature(s) inhabiting floor 20.

I think the proper question is - what so special about floor 10? Food, maybe, but that's about all you could likely count on. Any advantages to living on floor 10 likely would cause a creature to inhabit that floor (barring major disadvantages). The fact that floor 10 (or floor 20) is not inhabited by creature X automatically implies that there is some disadvantage in that arrangement, regardless of how powerful the monster is.

  • $\begingroup$ Yes it's a crazy-broad question. The real answer would be "because of why they do - something that makes sense". Then you give several examples of reasons that make sense. $\endgroup$ – Dronz Jun 25 '16 at 20:56
  • $\begingroup$ @Dronz Thanks. =) I like to believe the best fantasy worlds have some consistent logic underpinning them. =P $\endgroup$ – Anaksunaman Jun 25 '16 at 21:50
  • $\begingroup$ I heartily agree! $\endgroup$ – Dronz Jun 25 '16 at 22:12
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    $\begingroup$ For some reason I read the "Free Will" title as "Free Wifi", and I just got this image of the monsters all sitting on their tablets until the characters turn up, and they're not really aggressive monsters, but they were in the middle of a raid... $\endgroup$ – Rycochet Jun 27 '16 at 9:38
  • $\begingroup$ @Rycochet Lol! That's awesome. =) $\endgroup$ – Anaksunaman Jun 28 '16 at 1:04

Natural selection

Over the ages the inhabitants of the dungeon have adapted to the features of their homes: darkness, temperature, air pressure, local gravity anomalies, contaminants in the water, background radiation, seeping oil fumes, fungus spores. Just as you are not used to these effects and are weakened by them, so too are they weakened when they are missing. So we would expect that they would wander slightly but they will be most common in the places where they have the most advantageous adaptations (which is why many games make the monster distributions probabilistic rather than precise). Only by gaining some tolerance to those features, whether natural or artificial, can you neutralise their advantage against you.


They prefer to let their food come to them, eating adventurers that enter the dungeon, along with their supplies, and/or the corpses of the monsters that the adventurer managed to slay.



The creators of the dungeon put the stronger monsters in the deeper, higher security areas, to make it more difficult for them to escape and threaten the society on the surface.


I don't know if this logic entirely holds, but lighter monsters tend to be more migrant. Monsters at the top and more accessible part of the dungeon would be cleared out more frequently. It would take a creature that populates more frequently and can move in again quickly to establish some sort of hold on a dungeon. The lower floors aren't bothering people so frequently so they aren't seen as being worth clearing out at regular intervals, so larger entities or more powerful swarms can establish a foot hold.


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