Welcome back to Dungeon Designs and our discussion of “The Living Vault” – a dungeon which aims to feel more alive than any other in existence. Last time, we went over the basic stats for the Living Vault as a creature and an active participant in players’ dungeon crawl. This time, though, we’re going to be focusing more on the actual “dungeon” aspects of this concept.

And don’t worry – anatomical expertise is not required because I sure don’t have any.

Wait, What’s a “Living Dungeon” Again?

As a quick refresher, let’s look at what we established last time. The Living Vault (often shortened to just “Vault”) is a concept for a dungeon crawl. In this concept, players will explore a dungeon which is, itself, alive in some way. The original concept was meant to use an aberration theming with grotesque innards and similar visuals – however this concept can just as easily be used with any number of less disgusting themes.

The purpose of this concept is to create a dungeon experience where the dungeon itself plays an active role. Rather than simply being a setting, the Living Vault is a character in its own right. Furthermore, this allows the Vault to have concrete in-game stats and action options, which makes the dungeon more dynamic.

Now, the stats of our Vault are simple. It has a high HP, a low AC, and a damage threshold for defense, and then a weak attack, a powerful grapple, and an area denial ability for offense. Outside of combat, the Vault has the ability to modify and adjust traps in order to adapt to players’ actions.

In addition, the creature itself is blind and relies on the resident monsters to “see” for it. This creates a two-phase system. While in combat, the Vault is an immediate concern. Out of combat, it cannot see players and so can only actively create hazards where it thinks the players might go.

This doesn’t cover everything, but it’s enough for us to continue on. Check out the original post for more details. For now, let’s move on to how the dungeon is laid out on the inside, and what this concept means for the physical design of the dungeon itself.

Anatomy of a Dungeon

Firstly, let’s look at how to make the dungeon feel like a complete being. Some of these examples are tied to specific themes (like eldritch monstrosity, living grove, etc) but most of the mechanical effects can be adapted to any theming.

Last time, I brought up the idea of having certain rooms of the dungeon reflect the Vault’s abilities. If the Vault has an endless supply of hostile constructs to assault players, where does it create them? A biological Vault could spit acid from the walls, but where is that acid produced?

I’d start by thinking about the Vault’s capabilities and considering what facilities or resources would be needed for each one. I’ll list a few of the more theming-agnostic options below, but remember that the specific theming of the Vault might offer additional options.

• One constant of a dungeon crawl is a seemingly endless supply of monsters to fight. With our Living Vault, we can directly address this by establishing where all those monsters come from. Thus we have the “spawning room” – though it could just as easily be a magical assembly line or a druid-blessed beast den.
• Another important function is resource generation or gathering. If a Vault has poison-dart traps, it needs a way to produce or store poison. In addition, we can assume that the Vault itself requires some form of energy in order to live and be active – this energy-production room could be a garden of sun-soaking leaves or a horrific stomach full of digestive fluid.
• Finally, one last option is to have the Vault include a seemingly useless room which has importance to the Vault itself. Perhaps the sentience of the Vault feels trapped and is trying to produce a mobile body for itself, leaving players to discover a bizarre laboratory or cloning vat. Or it could center on a memory – the very first room of the dungeon to be created holds a special place in the Vault’s mind, and it preserves it in a form as close to its original form as possible.

Effectively, we have the Spawning Room, the Energy Source, and the Pet Project as different options. Each one should have its own unique dangers, rewards, and functional effect on further exploration.

Let’s look at each one in a bit more detail. After that, we’ll move on to examine some of the most classic “living dungeon” tropes and how to use, avoid, or subvert them.

The Spawning Room

The Spawning Room is the place where all monsters present within the Vault start. It could be a specialized summoning circle, dragging in monsters from other places. It could be a literal spawning pool, where bizarre growths turn into hideous aberrations, or it could be an assembly line where automated processes build construct soldiers.

This helps answer the classic “where do all these things even live?” question present in most dungeon crawls. Many old dungeon crawls paid little attention to this – there were always random encounters, and where those random monsters came from was of little importance. Later dungeons tried to address the issue with numbered lists of how many of a certain creature lived within the dungeon, but that had its own issues.

So, this is the room where all the monsters come from. That means there should likely be a fight in this room – and a quite big one at that. To me, though, you wouldn’t want this to start as a big fight. Instead, I’d have only a token force of monsters actually present in the room. But then, each turn at initiative 20, a certain number of new monsters would be added from the room itself rather than as reinforcements called from other areas of the structure. The goal would be to make players really feel how central this room is to the Vault’s ability to fight.

That being said, you don’t actually want to make all the fights in the dungeon that much easier once the Spawning Room is taken care of. You want there to be a tangible effect… just not that one. My preference would be to rework “reinforcements” and random encounters.

Reinforcements are a classic tool to help make a dungeon feel more alive. After all, if you hear your buddies over in room 7 getting killed, wouldn’t you go help? Or at least check on them? This is even more obvious if you’re looking at some sort of organized force – soldiers don’t just sit around and listen to the gate guards die. They go over and help.

For the Vault, I’d have it so that either individual monsters or the Vault itself can call for reinforcements. This shouldn’t happen every turn, and it should only happen so many times per fight. It also shouldn’t happen every fight. But as long as it happens a couple of times, you’re in a good place.

Because after players sabotage the Spawning Room, those calls for reinforcement… shouldn’t work. Monsters call out for help and get no reply because there aren’t spare monsters around anymore. Since the party destroyed the Spawning Room, the Vault can’t afford to have “wandering” monsters anymore. Everyone is assigned a place to guard, and they have to stay at those posts.

As hinted above, destroying the Spawning Room should also affect random encounters. I wouldn’t want to get rid of them entirely, but there should definitely be a noticeably lesser amount. Another option is to take all the random encounters and remove one or two monsters from them.

Now, this also depends on how much you used random encounters before the Spawning Room. If they never really came up, well… players won’t notice their absence. Simultaneously, even if they did have a few random encounters, if they just suddenly stop having them altogether they may not realize the difference – it can be difficult to note the absence of something.

Depending on the party’s level, you could also represent this by having some of the random encounters replaced with trivial forces. Things the PCs can deal with in a single turn. Even if random encounters were never too difficult before, such an obvious downgrade in certain encounters would easily let players realize that their sabotage of the Spawning Room has significantly weakened the monsters in the Vault.

The Energy Source

Everything needs energy. Running a full dungeon of interactive traps and attendant monsters is going to require energy of some sort – whether that’s fresh meat, raw magical power, or the souls of the innocent. Or, for the druid-blessed living grove, photosynthesis.

I’m going to touch on this more a bit later as well, when discussing the classic video game locales of “the stomach” and so on, but I still want to look at it here too. Because it’s a simple thing, but a very important one for establishing a feeling of “being alive.” Everything needs energy.

Now, the realities of this part rely a lot on the theme of the Vault. Players visiting the power plant of a construct Vault can expect a very different experience than a party diving into a foul, aberrant digestive organ. But regardless of the specifics, I think the most important concept here is “stealing.”

Whatever players do while in the Energy Source should feel like they’re taking something away from the Vault. That could mean burning up the food in its stomach, starving it. Or they could steal magically-charged jewels for their own use. Whatever works.

In my mind, this theft can have a few different effects on the rest of the dungeon. I would also want players to gain something, but that’s negotiable. Here are a few options:

• After stealing the Vault’s energy source, the creatures within the Vault become weaker. They act hungry or tired – giving either an in-combat drawback, or maybe allowing players to skip some encounters entirely.
• Whatever energy source the Vault uses is just as usable by the party themselves. It could take the form of a magic weapon or wand, or it could simply empower them in a passive way. The Vault, of course, would lose this benefit after the theft.
• Players could also turn things around and add something instead – a poison introduced to the Vault’s systems. This could be a literal poison, a weedkilling chemical, or a magical corruption. In a way, they’re stealing the Vault’s vitality and weakening it.

Again, this part is a lot more contingent on what the Vault’s theme is, so I’m not going to cover it in as much detail.

The Pet Project

Honestly, this could be nearly anything you can imagine. Whatever it is, though, will say a great deal about the nature of the Vault and its identity as a character. This is the personality piece, and there’s two main directions I can see this idea going in: desire and origin.

All characters want something – “what’s my motivation?” is a common joke for a reason. So if the Vault is going to be a character, then it needs to want something. And when looking at what someone should want, a useful place to begin is looking at what they don’t have that others do.

For the Vault, this could easily be freedom. Creatures like the party are capable of free movement and exploration. They can simply pick up and walk somewhere else – the Vault can’t. It makes sense for the Vault to be able to send its monsters (its “eyes” essentially) out to survey its immediate surroundings, but if they can’t move any further then that’s bound to cause curiosity. Perhaps it’s the sea, or a river, which despite being in sight is just out of reach. Or maybe it’s a settlement, with scared residents too afraid to draw close. All the Vault needs to sate its curiosity is a smaller, more mobile body – and there are plenty of horrifying ways to get one of those.

Another motivation could be loneliness and/or boredom. The Vault was (presumably, see below) created for a purpose. Guarding something, perhaps. But what is a guard without thieves to stop? Answer: bored. Then you have to remember that the Vault is meant to be a sentient creature. Sentient creatures tend to get lonely, so why shouldn’t this Vault feel the same? In both these cases, the Pet Project is most likely to be some sort of lure. Something that allows the Vault to attract new victims.

It’s a bit harder to talk generally about Pet Projects based around a Vault’s origin or creator since that changes drastically depending on the theme you go with. But we can still look at a few basics.

The first question is whether the Vault was created by something with a human-like consciousness and perspective, or if it was created by a higher entity with an entirely alien set of goals and methods. Whatever the case, the Vault likely would inherit its own perspectives from that of its creator. A human-made Vault could have very mundane desires, while a divine/fiendish-made Vault could be more inexplicable.

Next we need to decide whether or not the creator is still interested in the Vault or if it has already served its purpose. Is it truly just a Vault, built only for the creator to lock the door and throw away the key? Is it an active experiment or ongoing project that the creator is likely to return to?

We can then decide whether or not the Pet Project was part of the original plan or if it was created later. Perhaps the Vault’s Pet Project is a replication in miniature of another of its creator’s creations, like a child copying their parent’s work. The Vault could be making its Pet Project for its creator – something to gain their attention if they’ve been left alone, or maybe even a cozy living space for a creator who occasionally comes back to visit.

Ultimately, the Pet Project is a chance to explore the narrative behind your Vault. As such, it primarily serves a storytelling purpose rather than a mechanical one. Where the other rooms can change the nature of fights or alter the way the party explores the dungeon, the Pet Project is first and foremost a chance to elaborate on the story.

You still need a reward for the players, of course. A magic item, or maybe a hint at the “secret method” needed to kill the Vault. One option I think is particularly interesting is a special map that shows an always-accurate outline of the dungeon, in case the Vault is capable of changing where its hallways lead (we’ll come back to that in a bit).

Tropes and Clichés of a Dungeon

Now let’s talk a little about common clichés for the “inside the monster” dungeon. This applies the most heavily to the “eldritch abomination” theme, but I think it’s an important issue to address.

To start, we should establish that these tropes aren’t inherently bad. Commonly used ideas are commonly used for a reason, after all. But it’s still good to innovate, and avoiding common tropes is one way to ensure your Vault is memorable.

Now, many of the concepts included above echo these same tropes. The “Energy Source” is just a stomach by another name, after all. But I hope that by stripping away the theming from these concepts it’ll become easier to explore their ramifications without feeling beholden to past examples.

One thing I want to address in specific, however, is what I feel is the most damning element of these “cliched” themes. And that is, of course, the question of why does my monster’s stomach have a puzzle inside of it.

Or a riddle, or a staircase, or a locked door.

Basically, there’s a level of suspension of disbelief that goes along with any of these “giant monster’s insides are a dungeon” concepts. But I believe that it’s that suspension of disbelief itself which people grow tired of. They’re sick of the insane logic of needing to find a key in order to unlock a hallway which is literally the creature’s esophagus.

So how do we avoid these? Well first, let’s look at what dungeon elements are likely to cause issue. And note that while this discussion is quite focused on the “monster’s innards” or “aberrant growth” themes, similar issues might apply to the other themes as well.

First off are the mechanical bits that any functional structure contains: doors, locks, stairs, etc. These are somewhat necessary to keep since they define a large amount of the “dungeon crawl” experience, and you also don’t want to complicate them too much because it’ll feel off-putting for your players.

Many games simply ignore this, or just put a “biological” type texture on it and call it a day. And there isn’t anything wrong with that. In my case, however, I would want to explore things a bit more fully. My preferred answer, then, is to eschew keys in favor of a pheromone or hormone system. Essentially, players find “keys” which are just chemical markers which then allow them to open the “door” (probably a membrane).

And while this could be done through an item, I actually like the idea of getting more weird with it. Players find the “key” room and essentially are marked with the corresponding pheromone – when they come near the door, all they need to do is touch it and it will open. This shouldn’t have much of a mechanical effect, but the fact that it could have one at all is nice in my opinion.

As for things like stairs, there’s still more to explore. Rather than rigid staircases, you could make these simple slopes – what effect would that have on fights in the space? Slopes would also be good to facilitate moving hallways – if “stairwells” don’t have actual stairs in them and instead just slope up or down, they could easily change to become flat hallways.

The second big issue with this is loot. There’s a certain assumption that a gigantic monster could easily swallow loot from hapless adventurers, but it still feels a bit off. “I’m inside the tarrasque, exploring its organs like a dungeon, and still my reward is 10gp and a potion of healing.”

My original plan for this concept was set in Eberron, so I had a fairly easy “out” for this one. Symbiote items are a perfect way to keep dungeon rewards properly themed while still giving them out. That being said, there are other options as well.

For money, you can always use some biological piece which is easy to carry and worth a given amount of gold to alchemists or other craftspeople. This could be scales, or bones, or it could be utterly disgusting (“what, you didn’t know all potions use Vault monster bile as a base?”).

I also feel it’s important to embrace the “swallowed adventurer” as a loot source. Don’t feel like you have to give random wandering aberrations access to magic items (unless they’re infested corpses or some similar concept). But it’s just as important to keep in mind that the theme of an item is always yours to decide.

A rope of climbing found in the Vault could be a tendril ripped from one of the walls. An ioun stone could be essentially a kidney stone. And an alchemy jug could be a special gland. The point here is that these are not symbiotes. They aren’t “magic items” even. They’re just natural byproducts or components of the creature which, when removed and given to the players, fulfill the same purpose as magic items.

Of course, this all only applies to more biological Vaults. And I really do want to separate this concept from that one, singular theme. So let’s finish off with a simple list of things to watch out for.

• Locks, doors, and gateways. Remember that these things are often necessary, but keep in mind ways you can stress the difference in your Vault.
• Pillars, arches, and other architectural features. These things can sometimes be removed altogether, if you want. We don’t have support pillars in our stomachs after all, so why should the Vault? But also know that it’s okay to reimagine them as well – rib cages of bone supporting the ceiling is still a neat concept.
• Staircases, handrails, and other accessibility features. There is no OSHA for Living Vaults. For most of these, I say just remove them. You can keep some of their effects to make sure players can actually explore the place, but you don’t need to keep the visual aspect.
• Light. Now here’s a tough one. Bioluminescence is a well-documented phenomena in the real world, so there’s plenty of options for what is causing light. The important consideration here is why that light is needed. If the Vault’s minions all have darkvision, then there isn’t much need for light now is there? You can emphasize this by only having “natural” light in places where the Vault or its minions need it.

All of these issues can be solved in multiple ways. Just remember that simply reskinning everything isn’t always the best option. Consider ways your Vault could be special – a garden Vault could use vines to the exclusion of ladders, while a construct Vault might have literal elevators rather than staircases.

Obituary of a Dungeon

I hope that these posts have been able to adequately explain why I find this concept so appealing. I still haven’t made one myself, and I don’t know if I ever really would. But the concept is solid and the implications are exciting, and that’s what I’ve tried to express here.

But before we wrap up, there’s one last question to answer – what happens when the Vault dies?

Ultimately, the answer is… “whatever you need to happen!” You could force a Metroid style escape sequence with players rushing to leave before the whole thing crumbles around them. The Vault’s corpse could remain stable – just lacking the more active interactions. You could even just let the Vault live on – all the PCs did was remove the corruptive or evil element from it. And now they have a semi-sentient and friendly structure, if they want one!

The important thing in all of these cases is to make sure the PCs can immediately and easily see that they’ve won. That’s easy if the whole place self-destructs. But if it just dies, leaving its corpse behind? Have things break and fall apart in minor ways as the party leaves (or allow them to skip by any remaining encounters as the monsters begin to feast, scavenger-like, on the Vault’s remains).

And if the Vault lives on, just freed from its malicious nature? Make getting out easy. If the Vault can reconfigure its layout, it should make a direct hall for the players to leave. If they need rest first, it could create a rest area for them. In either case, while the players remain inside the Vault, it should interact with them in a friendly way. A character slips slightly, only for the Vault to gently nudge them back onto their feet. Maybe it waves as they leave.

If I have one regret, it’s that I wasn’t able to explore the hidden strength of this concept – the dungeon as a character. It’s a Living Vault, after all. It can have personality, an attitude, and even if it can’t speak there’s plenty of ways to make its nature clear.

Unfortunately, that aspect of the concept is heavily tied to the theming. I didn’t want to get too in-depth on any of those for fear of locking people into seeing this concept in a particular way. Maybe sometime I’ll go over my own favorite interpretations.

But, for now, that has been the Living Vault. I have more design concepts that I’ll hopefully be able to come back to, but I’m glad I started with this one. It’s definitely the most lively of the ideas I have at the moment.

As always, let me know what you think!