Dungeons Part Four: Threat Structure

July 19, 2014

So, important confession time: the order of these posts is about “takeaway value” and modularity for you folks reading, rather than the order in which I use these ideas to make a dungeon.   Pretty much everyone can see the value in better design flow from playing stuff like Metroidvania games, and everyone has probably played a dungeon crawl that worked in a way very different than what they wanted in terms of Exploration/Logistics/Tactics, so those ideas are easy to pick up and plug into your own dungeon design.   The specifics of running a dungeon only make sense in light of those two ideas, and although this is the fourth article, it’s actually the first conceptual step I take before I draw any map or look up any monsters:

Threat Structure

Threat Structure is an idea of how the dungeon overall should be populated, set up, and react to the player characters.  It’s a very different experience between poking around and fighting off bits of wildlife in a tunnel system vs. wandering through a giant clockwork dimension created by a mad wizard who can reshape it a will.    Not just in colorful description, but also the way the monsters react – do they run?  Do they set up traps? Do they cooperate and mob you?  This is the game design part that’s worth considering.


Many dungeons are “critter” dungeons – they’re full of random monsters that either live in a natural habitat zone or have moved into some place that has been abandoned.  Critter dungeons might have a few small groups of intelligent creatures, but mostly the dungeon is things with animal-level intelligence.  You can get a good variety of threats in this kind of dungeon.

Critter threats are often predators or things fighting back out of fear.  You get stuff like alpha predators, pack hunters, ambush predators, poisonous things, and swarms.    Monsters don’t cooperate, so it’s easy to keep the encounters from snowballing into mob rushes.  A lot of the creatures can be driven off, which makes some fights easier, but it can also mean the players might have to deal with a monster that keeps coming back to try and pick them off.


A Lair is a little different than a critter dungeon, in that there’s one dominant monster or a species.  There may be a lot of other types who live on the side or are otherwise not interacting with the main creature(s), but most of that ecology is shaped by that central focus.  This might be a theme like if you have a poisonous dragon, that most of the creatures who live here have become poisonous as well – by absorbing the miasma it gives off…

Lair threats are an alpha predator or predators that shape the whole ecosystem.  Other monsters avoid these things.  These monsters are experts in most of the terrain, have hunt zones they know very well, and will violently protect their territory.  If the animals have good senses like smell or hearing, the party’s location might be easily tracked at all times, leading to some very scary games of cat-and-mouse.


A Mastermind dungeon involves an intelligent being of great power that actively sets up the dungeon as a place of defense.  They may or may not fix everything up, but they’re definitely using and manipulating the monsters within for their own safety and exploitative needs.  This might include breeding or magical enhancement to improve them.

Thematically, a mastermind dungeon might be known and feared (“A Vampire lives in those catacombs!”) or it might be something the players only discover after they’re in the dungeon.  It can be quite horrifying to realize what you thought was random critter ecology was actually engineered by someone on purpose.

Because there is a Mastermind running the dungeon, you can be assured they will take action as soon as they feel there’s a problem, to either get rid of the intruders, lead them off the right track, or otherwise improve their defenses.  Masterminds tend to make nasty traps, magic, or use of environment with their monsters, and you may have a few powerful lieutenant monsters that work to patrol the dungeon and modify the defenses as intruders attack.


A Fortress dungeon is an area that is dominated by one large group of intelligent creatures, that work together in an organized fashion.  This might be your classic Fortress of Orcs, or it could be a colony of giant ants.  Either way, they have a large organized social structure, work well together, and will adapt quickly if problems develop.    In my opinion, this is one of the most dangerous threat structures, if only because it’s so easy to get mobbed, and the creatures will adapt.

This is a kind of dungeon where the value of information scarcity flips over to the players – the party are the ones trying to stealth their way in, and getting discovered will lead to a hard fight or likely loss.   Unless the monsters have moved into a cave system or ruins of another space, it’s quite likely that the dungeon will be relatively well laid out, and thus, not as confusing or maze like.

You don’t get a lot of monster variety or hazards in this kind of dungeons, which usually makes it less likely to be used.  The D&D Against the Giants type modules worked because the issues of being human sized in giant-zones meant their normal furniture, etc. created the hazards and complications rather than collapsed tunnels and ruined bridges.


Faction dungeons are have several intelligent monster groups which are working at odds with each other.  This may be a cold war tension between them or out and out violence.  These are great for doing dungeon politics type games – players can take sides, set up groups to fight each other, etc.

Like the Fortress type dungeons you have groups who are organized, and there is a possibility of getting mobbed, but because the groups are afraid of getting overwhelmed by other groups, they’ll often play defensively – only committing some of their forces as to never leave things like their food supplies or treasure, unprotected.  Adaptability can be quite high, and while there may be traps, most are probably deterrents or “alarms” rather than  anything else.

A tricky thing to consider is this: if you have all these groups who are raiding each other, trying to stay alive with whatever resources they can get, what is their first assumptions about intruders/newcomers?  What is that assumption like if they see you fighting their enemies?  What is that assumption if you’re fighting their allies?  What if you come across their bodies from a skirmish they had with someone else, but a witness sees you and assumes you did it?   Are their racial or historical issues affecting it too? (“They hate Dwarves.”)  This shifting role of views and attitudes can turn this sort of thing into a very interesting space for rolelplaying and political moves.

Tying it all together

This is the actual process I use, in this order.

1.  What the Players Want (length of game, interest in a single dungeon, Exploration/Logistics/Tactics ratio)

2.  Concept/Theme+ Threat Structure 

3.  Draw the map and give the actual dungeon layout using fun play tricks

4. Specifics of Monsters, Traps, Hazards, Puzzles, etc.

Steps 1 & 2 go quickly for me – usually this is a 5-10 minute process since I know my players, have a good idea of how long they’d like to commit, and then just need a cool idea for a dungeon.

Steps 3 and 4 I prep just enough for 1-2 sessions at first and that takes 1-2 hours for crunchy games like D&D 3E or 4E.  Since I usually run a 2-4 hour session game, I know how much engagement density the players will push through, and can prep accordingly.  After the first session or two, that prep time drops to 30-45 minutes a session.  If something like Tunnels and Trolls, then we’re talking 10-30 minutes prep at most.

Prep vs. Payoff Balance

One issue is that as you play higher level games, the players get access to all kinds of movement options (burrowing, phasing through objects, teleporting, etc.) that can let them leapfrog a lot of areas in a dungeon.   This means you’re going to have to prep a lot more dungeon as the amount of prep time you do provides less and less guaranteed engagement density.

This becomes killer if your game system also has a narrow range for balancing encounters – you have to prep a lot more with more detail, but you also may have the party jumping ahead of where they should be or missing expected resources or magical items because they skipped ahead (or, they might have an easier time escaping or luring a fight to somewhere you don’t expect because of these abilities.)  This can be one reason you see GM burnout- you’re doing more and more work to get sorta the same play balance, but it’s just getting harder and harder to catch up.

Next: Information Management (Aka, how do I organize all of this?)

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