Why might any self-respecting dungeon engineer employ a booby trap which isn't lethal?

Question

I've been thinking on it for a while, and it really doesn't make sense.

If I'm a medieval dungeon engineer, designing a dungeon which will guard my vast riches, why in the world would I install a booby trap which isn't lethal? If I'm going to place something akin to the wealth of a nobleman in this dungeon, surely I have the funds to use deeper pits, sharper spikes, more arrows, more potent poisons, bigger rolling boulders, or more spell-casting scrolls.

However, I frequently see these groups of adventurers who waltz in, plunder the dungeon, and waltz out with other king's well earned gold without so much as a broken leg!

Why would those people make it so easy?

I should surely make my traps with the intent to kill the most legendary foes!
Merlin the wizard, Tiamat the terrible, and Xanathar the knowing will not be able to leave this dungeon without leaving their soul!

Specifically I'm speaking of booby traps - not alarms, not guards, but plain, damaging traps.

Bonus points if it fits within the narrative of Dungeons and Dragons 5e, or Pathfinder settings.

Answer 1

Dead Men Tell No Tales

Suppose you're a rich viceroy or a dragon, or really just anyone that a band of adventurers / thieves might want to rob in D&D. Sure, you can make some really deadly traps, like using an Orb of Annihilation, but that doesn't solve one of your main problems. Getting constantly attacked is annoying. Here's the thing - thieves don't operate in a vacuum. So what you do is you solve your pesky problem with non-lethal traps. That way, the target is alive and thus you can do various things to solve the problem that you're being robbed.

You can, for instance, if you happen to be a dragon, rake your claws down the hapless thief and horrifically scar him before releasing him back to the rest of the humans as a warning. You can also, if say you're a rich man who has been previously burgled, hand him over to the torturers to find out the who the thief sold the goods to. And, say, you're the BBEG Overlord. You can use your nefarious Cthullu-esque mental magic to read the poor rebel's mind to find out about the rest of the rebellion, allowing you to put them down with ease.

In short, information is a valuable commodity, and it can only be capitalized when the subject isn't dead. (*Unless you're a powerful necromancer, but necromancy tends to be expensive, at which point it's more of a cost effective measure.)

Answer 2

Same reason why modern armies use small arms, that are less deadly, than they could be. If the trap outright kills the unlucky adventurer, they party can just leave the corpse and press on. A wounded member of an adventuring party binds up resources. They spent time, bandages, potions to heal him, maybe he is hurt so bad, that they have to carry him around, seriously slowing them down. This puts stress on the party, leaving them vulnerable to the next line of defense.

Other reason: Maybe they want prisoners to interrogate, as livestock, slaves etc.

Answer 3

I Think It Depends on What You Are Hiding, and Why

The Treasure and Trap May Be Interacted With Daily

In King Solomon's Mines there were the eponymous diamonds mines of King Solomon.

Mine managers needed a place to store raw diamonds pulled from the earth between caravans hauling the goods back home, which (since the mines were remote) could be months, or even years.

The trap was deadly, but something the managers could interact with every day w/ minimal risk: a extremely heavy secret door led down a long hallway that ended in the diamond store room. Only the managers (of which there were only a few) knew of the door or how to open it.

The door was on a timer, and would close a few minutes after opening.

The trap in King Solomon's Mines was deadly, but not instantly so (you died of starvation, or suffocation). Managers using the store room didn't need to remember what the trap was. They need remember only the far more general rule : the store room is trapped; do your business quickly and get out. Also, in the event a manager was trapped inside, one of his/her peers on the outside could notice their colleague was overdue, and open the mines themselves.

Additionally, as the heroes figure out to their salvation, the engineers who were building and testing this trap didn't want to get locked in for every successful test. They built a back door to the storehouse, that the heroes intuited must exist and which, with a little searching, they found.

The Treasure Might Be Yourself

In the Curse of World War II Gold, members of the Japanese military were trapped by an invading army inside a network of tunnels in a foreign land. The imperial army had been looting riches from the government and people of all nearby islands and, since the regional command was stationed here, concentrated with this Imperial force.

Trapped in the mountains, most of the deadly traps laid : land mines, poison gas, pits, cave-ins was meant to protect the army from the enemy.

Meanwhile, the general ordered the digging of deep pits, around 200 feet deep). These pits weren't trapped. They were even marked in layers of material not native to the island as the pits were being filled-in, so that people retrieving the treasure could know they were digging in the right spot.

The pits require an enormous amount of labor to unearth, so this effectively protects the treasure against random soldiers fighting back-and-forth for control of the territory. Someone must possess a stable hold on the land, and the ability to put a sizeable workforce together (hopefully the victorious Japanese Empire) in order to recover the goods.

Because the soldiers were trapped in the mountains, the untrapped treasure pits were in the midst of trapped tunnels.

Or, You May Only Plan on Coming Back for the Treasure Once

In Goonies the crew of One-Eyed Willy found themselves running from the British inside a coastal cave. The entrance to the cave had been collapsed by British cannon fire, and One-Eyed Willy's ship and crew had been sealed alive.

One-Eyed Willy's engineers manage to dig their way out of the cave. The captain and crew has a dilemma: they are far behind enemy lines; it will take them months, maybe even years to - get home, recruit a new crew, and get ships back to this spot.

In this case Willy orders the construction of traps that, hopefully, they will only need to evade and disarm once. They plan to come back and empty the treasure cave, never to return.

In this case, deadly traps keep the locals from working together to get at the treasure cave. Anyone accidentally finding the cave and traps is, hopefully, silenced immediately.

Unfortunately, Willy decides to poison his crew at the last celebration before they depart for the wilderness. And the crew decides to poison the captain as well.

Meant to Stay for Generations

In The Curse of Oak Island a treasure was buried in a 200 foot deep pit, protected from outsides by a network of trap tunnels that would allow the seawater into whatever workings you dug, spoiling the pit. The traps weren't necessarily lethal, but easily could be.

In this case, probably, the treasure was meant to stay put. Possibly indefinitely.

Many of the theories involve that communications about the treasure include principals for disarming the traps (such as the location and existence of the traps intakes of ocean water).

Similarly, in Aladdin, the entire Cave of Wonders is filled with poisonous treasures. The treasure is the trap. Only someone who knew what the real treasure of the Cave of Wonders is, the genie lamp, would be able to retrieve it. The lamp could be hidden that way for generations, as the way of defusing the trap is a very simple rule : only touch the lamp.

This way, whoever built the Cave of Wonders kept the extremely powerful genie lamp within reach (should a national emergency occur), and could pass the secret to getting the lamp to his/her descendants; but at the same time, the extremely dangerous lamp was kept out of reach day-to-day.

Never Meant to Be Found

In Temple of Elemental Evil a deity of fungus oversteps it's bounds and becomes imprisoned at a location on Oerth. To keep anyone from ever releasing the fungus deity, layers of very deadly traps were constructed.

In this case, the traps are never meant to be circumvented. The goal is to keep everyone out of the god's cage forever (or at least a very long time).

Answer 4

The Treasure is Bait

Gold is not food [citation needed], and Adventurers are an excellent source of protein.

The purpose of the gold is to attract humans - it's a feature not a bug. It's a lot of work to go out hunting, so smart Dragons have arranged for rumors about treasure, and they simply wait for the food to come to them.

But Dragons are predators, not scavengers. They want their kill to be fresh, and enjoy the moment of the kill.

Of course, this way the horde becomes a self-fulfilling prophesy. The adventurers bring in gold and magic items, which the Dragon keeps around because its easier than hauling it away. Thus the treasure becomes real.

Answer 5

I'll borrow a theme from the real-world modern security industry. Quoting from Information Security: Principles and Practices, 2nd Edition:

Principle 1: There Is No Such Thing As Absolute Security

Given enough time, tools, skills, and inclination, a malicious person can break through any security measure. This principle applies to the physical world as well and is best illustrated with an analogy of safes or vaults that businesses commonly use to protect their assets. Safes are rated according to their resistance to attacks using a scale that describes how long it could take a burglar to open them. They are divided into categories based on the level of protection they can deliver and the testing they undergo.

Granted that, security is always a cost-versus-effectiveness tradeoff proposition. Among the troubling questions one might ask from the dungeon-designers perspective:

• Do I actually know the exact operational parameters of Merlin, Xanathar, etc.? (likely not)
• Are there other possible looters in the world with capacities unknown to me? (very likely)
• Will looter capacities change and evolve in the future? (also very likely)

Hence: the "upper bound" of looter capability is somewhere between unknown, not knowable, and constantly changing. In addition, it's probably beyond the resources of any organization to meet even in theory (as per the real-world security principle).

So one has to make reasonable judgements about risk-versus-reward and gauge the traps to that level. Also, assuming the dungeon-builders themselves want at some point to access the place, you'd prefer not to kill yourself with an overly lethal trap by accident.

Two observations about that risk-reward:

• D&D (for example) has a stark increase in capability and durability for advanced characters/heroes. A 10th level PC is something like 10 times the durability of a commoner, which is not a thing that exists in reality. So you can set traps that almost assuredly are really lethal to most people... but are not for heroes of 4th level (or whatever), who are possibly relatively rare in the world.

• Early editions of D&D tended towards a much greater degree of verisimilitude in this regard; it was fairly common for traps to be "save or die" or even just "die no save" if the PCs took the wrong action. While some of us still like that quasi-realistic, easy-to-die play style, it received a lot of complaints over the years, and has mostly been safety-bumpered out of more recent editions.

Arguably in light of that latter observation: Perhaps the legendary heroes and anti-heroes of the world are protected by the gods or supernatural forces such that there is simply no trap that can possibly catch them without fail. Dungeon designers are trying their best to make fully lethal traps; it's just that it's not an achievable goal in their world.

Answer 6

Maximizing body count is not even your goal

You don't actually care about how many adventurers your traps kill. What you care about is being left alone. There is no such thing as an impregnable defense. If you're going to booby trap something, what you want is an outer layer of traps designed to be extremely dangerous but not aim for 100% lethality. People spread the word 'stay the hell away from the Tomb of Hoarfrost' and quit coming around.

Not extending this "courtesy" actually serves to encourage a certain type of adventurer to try and break in, more or less for the same reason some of the best DRM-breaking hackers do it purely for the challenge.

Booby traps are not cost effective anyway

These things never existed in real life. People love using them in fiction because, well, they're awesome. But in general, the problem with booby traps is maintenance. The traps will need oiling. Dusting. Bows held at full draw for years will eventually foul and no longer fire.

Who's going to do all this maintenance?

People who work for you? They're not going to be big fans of hair-trigger death traps. This is the reason booby traps are illegal in the real world: the number of actual intruders they catch is far lower than the number of mailmen, utility workers, and so on that stumble into them. This is a good reason to use less lethal traps.

Or will you try slaves, so you don't have to care they don't like it? This might sound more attractive to the less ethically-inclined dungeon master, but it's actually a much worse idea. Now you've got to keep a permanent population of folks highly motivated to "betray" you (not that they ever even owed you loyalty to begin with). The results are fairly predictable.

Answer 7

As a preliminary warning.

It makes your neighbors annoyed with you if every time some drunken fool tries to break in, you kill him. Occasionally having to go drag him out of a pit and hand him back to his family is a small price to pay, especially if you can make it a humiliating experience, and it warns people that there are traps so they'd better not try it.

Additionally, the price for making and keeping up a simple trap may be much lower than a more deadly one. Why use up the rare and expensive snake venom from the tropics when a simple pit will do? Save the venom for the guys who get through the first three layers of progressively nastier traps.

Answer 8

For the same reason why there are people in MMORPGs who insist on playing against their own side, who spawn camp, who place teleporter entrances underneath your favorite hiding spot, who insist on standing in front of you so you can't shoot the dirty rotten rat on the other team. In other words...

Your Dungeon Engineer is a Psychopathic Griefer

But, really, how do you grief a couple of rangers, a paladin, your basic magic user, and some well-dressed dude sporting shuriken?

• In one section of the dungeon, there's one whomping powerful spell in play that causes all location spells to cause the party to always take the right tunnel, leading them in a perpetual circle.

• In another section of the dungeon the paths are all graded slightly to the left, forcing the party to either scrape their left shoulders against the wall or to hop slightly every other step, looking a bit like a teen be-bop band.

• A devious spell is designed to play disco music sung by a chipmunk just after he'd been nutted by an angry gnome — and every time you cast dispel magic the music comes back with a different NPC name.

• The skeletons are actually raven skeletons and they're under command to only peck....

• Every Kobold encountered by the party constantly chants, "trade your best hats at tradenpcdndforever.cc!"

• Every NPC has a girl's name — just to get your hopes up.

• Oh, and there is a treasure... you can see it occasionally through impenetrable bars, mirrors, and through cracks that can't be widened with any spell. But there's no way to actually get to the treasure!

Answer 9

Relying on traps alone to protect your treasure is a recipe for failure. A single competent thief with a 10' pole, a sack of rice tied to a rope, and 3-5 trained hamsters (among other standard tools) can slowly and methodically work their way through your dungeon, setting off the traps a safe distance ahead of them. If there's no time pressure, a thief could take days to make it through if need be.

That's why you also need minions to patrol the dungeon: if the thief knows that a patrol passes through every 15 minutes, they won't have time to search for traps properly, so they'll actually set a few off, injuring themselves and probably alerting the guards in the process. (If the thief doesn't know that there's a patrol coming, the problem solves itself once they get there.)

And I don't know about your minions, but mine always complain about poor working conditions if one of them gets decapitated every time they forget to only step on the prime numbered tiles on the way to the break room. But they don't whine nearly as much if it just drops them into a pit trap and they need to get call someone to fish them out.

Answer 10

Nothing as good as the answers we already see, but a few more:

Traps that start out deadly, if not maintained, become not so deadly. This can include:

• spiked pit that has already caught so many people over the centuries that the spikes no longer stick through the corpses

• hinged tilting floor that have enough bodies trapped beneath them that the floor no longer opens 90 degrees but now just 45 or something; you slide onto a big pile of bones and take some damage perhaps related to how much you're carrying. Meanwhile a party of 3 or more can make a "human pyramid" up the tilted floor to get back up to the doorway. (Put some treasure down there--belongings of the previous explorers--but if they're going for it, have a chance the party has a moment where none is holding the floor down at its 45 degree angle... letting it pivot back up and entombing them. So mere happenstance isn't deadly, but the greed is.)

• fast portculis that, due to wood rotting, only comes down half way, giving a good bop on the head instead of slicing you like a guillotine

• rusty swinging mace or similar that is now squeaky and slower, giving just enough warning to jump out of the way, and if it hits you again no longer deadly

• poison coating way past its "use by" date and merely burns your hand bad enough to keep from using it, not actually fatal

• bowstrings broken or bows have too much shape memory to be effective: the party steps onto a dias and arrows simply fall out of holes in the walls all around them...

• some kind of nondescript malfunctioning clockwork such that every time the party steps on location A, they hear scampering noises behind them down the hallway... no-one's there, it's just something that used to be fatal.

Another idea for a "working dungeon", say where a big boss NPC keeps his troops quartered: you don't want the stupid troops to get killed periodically (bad for morale!) so rooms with a one-way door weighted to shut--meant as traps--also have a gong to call for someone to let you out. Perhaps a barred window in the door is meant to see the bait from outside, and let a trapped minion call for help if inside. Or, it has a one-way secret door to get out of, or catch that re-opens the main door, so that the master can go in and arrange the gold-plated bait trinkets without dying himself.

Answer 11

Dead bodies are a hindrance; they bring disease, and stink up the place. A booby trap locks the person or persons in, and then you hand them over to @Halfthawed's crew for interrogation :-).

You might have ethical reasons against deadly booby traps, and consider them dishonorable. Or, you might be a bit dark, and take captured folks and put them in The Arena for your entertainment. That might warn off potential thieves as well.

Answer 12

There are two answers to this: the in-universe reason and the out-of-universe explanation... the latter being the most important.

The out-of-universe explanation is that it's a game... a challenge, not an exercise in frustration for the players. A dungeon with traps so lethal that it's 'Roll another character' time if you make so much as one mistake isn't fun, it's frustrating. Frustrate the players too much, and they'll go play something else.

So... when you get to the in-universe explanation, the out-of-universe explanation must still take precedence... so regardless of the supposed builders' motivations, certain design principles must be followed, that being the concept of challenge. You can't go from zero to lethal without some sort of buildup.

Secondly, a good dungeon design intended to function for a long period of time should not rely upon devices that are single-use or mechanically complex unless part of the design includes the provision for active defenders who will be both willing and able to maintain them... However having active defenders is also a weakness... you can't guarantee their loyalty or abilities forever, and sooner or later, they might start to wonder why they're still guarding the treasure when they could be helping themselves to it.

A good element of dungeon design should then include features intended to entice certain creatures to make the dungeon their home... you know the sort I mean: monsters who will either want to eat (or parasitise) treasure-seeking adventurers, or who are simply territorial, and will just want to kill them or drive them off. Ideally, these creatures won't actually be interested in the treasure.

Now, that's not to say that you can't have lethal traps, just that the rules of the world are such that there must be a challenge... and not so much a "Whoops, you didn't notice X, so you're dead now." So, you have to follow the rules, you have to start with weak traps and deterrents, and gradually build up to the more dangerous ones, or else provide foreshadowing in the form of the remains of previous adventurers, so that should any of the player-characters die, the GM can say, for example, "You didn't stop to wonder why I said that there were all those skeletons with shattered lower limbs lying around?"

It must be considered that the GM may be running a sandbox world, rather than a guided campaign, so at any point there may be challenges that are beyond the player-characters' abilities. The ultimate success of a dungeon from it's in-game designer's point of view must therefore be that adventurers arrived, attempted to penetrate its defences, and chickened out (and/or died) before reaching their prize... and that should they return, they would have to overcome all the challenges again, or perhaps new ones, considering that new monsters may have replaced those that were slain.

Now, a game world and the real world share certain fundamental truths on the subject of security:

1. The best security is obscurity. If no-one knows about a treasure, then no-one will attempt to steal it. That's not to say that someone might not stumble upon it, or that someone who helped to hide the treasure might not speak or write about it.

2. Allowance must be made for the failure of obscurity... meaning that you still need a dungeon to guard the treasure.

3. History (both real and fictional) has shown that you can't (usually) take your treasure with you when you die, and if you can, you don't stash it in a dungeon unless it is also your home.

So... since it is demonstrably better to bequeath one's worldly goods to one's descendants, there's no reason to do otherwise, except for three reasons:

1. No-one you know is worthy to be given your treasure, so your dungeon is a challenge intended to find a worthy recipient for it.

2. You delight in the torment of others, and your dungeon is a trap designed to inflict frustration, pain and loss upon them and their loved ones.

Or

3. You have been misguided by others into believing that you really can take your worldly goods with you when you die... or for some reason, it really is possible. Most likely, though, either your stuff is really just going to be a temptation to grave robbers, or some shady individuals are going to try to substitute cheap, trashy replica grave goods and make off with your valuables, in the expectation that your relatives wouldn't desecrate your grave, and so will never know that a switch has occurred. However, either way, there probably won't be much of value for others to steal... the liklihood is that someone else stole everything before your grave was sealed, or your valuables went with you/followed you to whatever afterlife you went to, and since despite all the magic in the world, the law of conservation of value is inviolable, so any loot-duplicating magic like your loot staying in your grave and also following you to the afterlife is not going to happen.

Answer 13

Deception - plain and simple.

Say your treasure is deep underground - you could have an elaborate series of traps and pitfalls - leading to a treasure chamber that looks like the real one, in a chamber shallower above the real treasure.

It has been plundered of course - and your thieves are feeling chuffed that they had 'survived'. Then they think - of course the treasure has been stolen by those that came before them.

They then return to their Thieves Den - reporting to their bosses and colleagues that they bravely and courageously went through the traps (and have the bruises to show for it) to find the treasure stolen. Whether they are believed or not, it is obvious the treasure is no longer at the site regardless and must be somewhere else now.

Future thieves would come to the same conclusion.

The long-dead owner of the treasure can rest assured that the best way to safely store his treasure is right under their noses, under the spot where the thieves thought the treasure would be.

Answer 14

1. Your treasure is important, and you kind of want to be able to get it out again. A bunch of non-lethal traps is a nice way of keeping your staff on their toes as they say "well, lucky I didn't fall into the spiky acid pit of DOOOOOOOM over there". It reduces the amount of new staff you have to acquire, and the amount of treasure that has to be retrieved by draining the aforementioned acid pit is also such a hassle.

2. Trouble keeping your vicious animals fed? Meat starts to rot so quickly after it has fallen into a spiky pit or crushed with a boulder. So why not keep the meat alive instead? The traps might be non-lethal, but the animal that drags you and your party into their lair and devours you one by one over the course of a few weeks will take care of that. It's also a nice way to test your traps for maintenance during feeding time when you put some prisoners on them. You don't want your trap to be rusted shut when a party waltzes over it right?

3. There are two ways to keep your treasure safe: make sure it's a secret, or make sure no one would dare touch it. When someone comes by the treasure obviously isn't a secret anymore, so better let the local bar get a retired adventurer as permanent resident and make sure he has a nick-name like Legless Bob or Danny the Cripple.

4. On the topic of secrets, before Bob gets to have a quick weight reduction below the hips it would be nice to know how he got to the trapped place anyway. That way you can remove any interesting murals, locals that talk too much about enticing treasure instead of mutilation, information brokers or whatever else that caused interest to be had in your dungeon in the first place. Such people could either quietly disappear, or when the secret is out too much they could have quite public and gruesome "accidents" happen to them.

Answer 15

It might also be that you want your treasure to be found

You're assuming the type of dungeon that's made by the evil or semi-evil wizard who gathered up a treasure and wants to keep it to himself. But there's another type: The dungeon that contains a legendary artifact that is only to be held by the worthy ones. Obviously then your traps would not be designed to kill, but rather to kick the unworthy ones right back out the door, correct?

Answer 16

The more deadly the trap, the easier it is to evade. Think of the ballista trap, a trip wire launches a massive bolt guaranteed to skew anyone it hit to death. But, it only hits someone if they're standing in its path. So duck and do the 'penitent man shall pass' and everyone will be okay.

Given thieves' and magicians' and clerics' ability to detect poisons, traps, predatory loans, and what not, it is a wonder that any trap ever hurts anyone.

So the trap that isn't a trap. A cream pie in the face, or a moat that the raiders have to swim through to continue. The filling or the water might not be deadly, could be half of binary poison that is administrated by a later trap. Or it's pheromones of a Martian Thark in heat and the some of the dungeon's guardians are bull Tharks. One whiff of you, and it's death by bunga-bunga.

Similarly harmless mold spores could be seeded along the dungeon. But they react at a later part, deeper in the dungeon, poisoning the water supply or busting into flame consuming everyone's food, spare clothes, and lamp oil.

Things like this would consume precious resources that raiders need to steal your loot without really doing any direct harm to them.

Answer 17

I'm surprised this has been overlooked but perhaps our current users are fundamentally too nice.

The trap fires more than once, the first victim is bait for the rest.

An adventurer triggers the trap and is now lying wounded and immobilised in the trigger zone. The adventurers will try to recover their wounded team member, the trap fires again. Repeat as required.

This will have one of the following outcomes:

• The entire party is caught by the same trap one at a time.
• The party loses two members to the first trap and then spends the rest of their time trying to get them out without losing any more.
• Two members of the party are caught by the first trap, from then on every time someone is caught in a trap they're left to lie and the rest of the group moves on with the echoing cries of their wounded friends following them down the corridors.

Answer 18

You are breeding a goblin army and need live wombs (plus the men provide decent protein for prior captures). Humans, elves and other females are able to birth larger litters than the purebred goblin females.

Even better if your goblins are actually asexual parasites and could breed the male adventurers as well.

Answer 19

Protecting the treasure isn't the point

If you build a dungeon, sooner or later, it's going to be filled with various creatures, from wolves to cave bears to goblins to ancient dragons. Frankly, as long as your dungeon is accessible and comfortable to the natives and wildlife, they'll keep moving in - especially if you seed it with a little treasure and some cheap magic items.

Of course, goblins and wolves are a lot easier to deal with than ogres and dragons, and a lot easier to replace, too. If you filled the dungeon with grueling death-traps, there's a good chance that you'd kill off even hardy mid-level adventurers, which in turn means a lot of their equipment and treasure will be going to the local monster population, attracting even bigger monsters, which may well remove your access and claim your dungeon for their own use. Not exactly a good return on investment.

No, deadly traps are right out. Instead, you want blunt arrows, shallow pits, rounded spikes, and feeble acid traps that wouldn't kill off a wizard with a -3 CON modifier, let alone an adventurer. You want your dungeon to be so bland that even a desperate mid-level adventurer would turn up her nose. Instead, you'll get a torrent of low-level adventurers, eager to break in their shiny new swords killing a goblin or two, and picking up a few paltry silver pieces for their trouble. Keep it easy, and the adventurers will keep coming back!

...And as long as they are visiting the "easy mode" dungeon, you can make sure they survive to spend their silver on the way in and on the way out, too, on cheap healing potions, basic weapons, and the leftover equipment from the few failed adventurers who couldn't dump sand out of a boot with instructions on the heel.

The real treasure was not the friends you made along the way, but the hundreds of gold pieces you bilked out of novice adventurers by selling overpriced healing potions.

Answer 20

Dead adventurers are a mess

Like, literally, they smell and then eventually they become bones. Inert bones, which don't make the dungeon more dungerous, but which cause lots of dungeon-upkeep problems; for instance, stack enough up on the spikes in your spike pit and the next hapless party lands with a squishy thump rather than immediate impalement. Likewise, a bunch of corpses bloated from poison is a dead (hah!) giveaway on the location of your hidden dart trap. And even worse than dead adventurers are dying adventurers, who will do things like get stuck in a puzzle room and then scrawl vital clues on the wall with their blood as they finally expire. Those cheaters!

No, better to just wound them a bit and let them carry themselves out. Much more sustainable.

Answer 21

They only want to capture the intruder.

Think about a lich. He needs to sacrifice live people in order to live, so wouldn't it make more sense to incapacitate the adventurers so he can sacrifice their souls later?