Dreadful Deeds: The DMS Trap

Today I bring to you the first of a few guest posts as I prepare to kick off my D5C initiative on twitter, it is written by the very talented (and devious) @Macrogeek so do yourself a favor and start following him on twitter if you’re not already doing so. The DMS trap is a wonderful play on a classic trap that could be found in any dungeon, a bit of a one-two punch but the twist is you’re PC’s minds will end up suffering some quite unique effects.

The role playing possibilities and hilarity that may ensue from the DMS trap are priceless so read on, and prepare to give me your best shot when I call out for D5C tweets starting next week. Also check back later today for another new Pixels & Polyhedrals baddie that will really choke your players for options.

The DMS Trap

Not all RPG traps should exist to try to cause a player death or TPK. Some of the best traps are the ones that give you, the DM, a plot hook to work from in future sessions. Thus I give you a trap designed only to cause fun role playing scenarios for your players – The DMS Trap.

It goes a little something like this:

Near the end of the dungeon the party triggers a trap. It’s not important how it’s triggered, just that it goes off.

Some ideas:

  • Have the “boss” character of the dungeon wear an amulet that triggers the trap if he dies or separates himself from the amulet. (a dead-man switch, he can intentionally trigger/drop the amulet if the PC’s don’t kill him, or it can go off when they take it from him as loot)
  • The trap can be triggered when the PC’s remove a certain goal item from the dungeon. They have to remove the item to complete a quest, but doing so trips the trap. Alternatively, when they fail a check trying to open a chest, or disarm what appears to be a simpler trap, the DMS trap can be sprung.
  • The fumbling NPC. Make the trigger for the trap obvious, supply a clumsy NPC who has much poorer skills than the rest of the party…have them fail a check. Works well with rescued prisoners, the village drunk, liberated henchmen, local politicians.

DM, you’ve made the players set off your evil trap…what happens next?

The door to the chamber slides shut sealing the PC’s in. Very scary ticking, scraping, clunking, and bubbling noises can be heard in the walls, floor, and ceiling of the room. That’s when they notice the ornamental holes in the podium, wall, ceiling, floor, whatever. You could pass this off earlier as a possible spike or dart trap, or just have the vents slide open as needed.

A thick noxious, smoke starts to very quickly spray up through the vents. It burns the eyes and causes the PC’s to gag and cough. If you have any pesky magic users trying to stop the smoke, or PC’s trying to hold their breath, have them make a series of increasingly difficult checks to continue holding their breath or cast spells, as the fumes will quickly overpower them or make it impossible to concentrate.

Once enough time has passed that everyone has breathed the gas, the clockwork noises in the walls wind down and the door slides open as the trap seems to have reset itself. You can have the characters rush out on their own, or if they failed spectacularly enough, have them wake up when the fresh air reaches their unconscious forms.

The strange thing about this trap is, other than being noxious, the gas didn’t seem to hurt them. Let the players speculate. Perhaps the alchemy components of the gas have lost potency over the years, or the trap malfunctioned. Maybe it was just to scare off intruders.

Or maybe their DM is about to have a lot of fun at their expense…

You see the DMS in the DMS Trap stands for Delusional Misidentification Syndrome. In a nutshell the disorder makes a person think that the identity of a person, place, or thing has changed, or can’t be trusted The PC’s have just been dosed with a rather powerful gas that will cause them to have some of the symptoms of DMS for a period of of the DM’s choosing.

There are 4 main variations, and you can roll a d4 for each party member and assign one, or just give the same one to the whole party.

  • Someone close to the PC has been switched with a identical replacement.
    “I know that looks and sounds like him…but I don’t think it’s really him. I don’t know if we can trust him anymore.”
  • Multiple people the PC’s meet appear to be the same person in disguise.
    “Doesn’t this shopkeep look familiar to you? I swear I saw him before.”
  • NPC’s that the PC’s meet appear to change identities with each other without changing appearance.
    “Did the innkeeper have that accent this morning? Is he staring at me?”
  • The PC is convinced that there is someone that looks just like him running around with their own agenda.
    “Sir…did you happen to see someone who looked just like me running around here earlier?”

This can be difficult to DM, but the Role-playing opportunities created should be well worth it. I’d recommend keeping notes on who will have which symptoms so you can keep your story straight. Remember that while the symptoms you describe to the PC’s should seem real to them, but they’re not real to the rest of the NPC’s. This means that perception checks can’t be trusted, because the delusion is inside their head.

It’s up to you as DM to decide if this is something that just runs it’s course and goes away after a few days, or if they need to embark on a quest to find a cure for it. If you send them on a quest, the next dungeon can involve puzzles based on identity. Mirror puzzles, illusions, henchmen and prisoners who appear to change faces, that sort of thing.


  1. This trap fails my #1 rule of dungeon design: there’s absolutely no reason for it to exist. Unless you’re in the hyper-specific situation of the lair of a harmless trickster entity who just likes to screw with people, this trap doesn’t make the smallest bit of sense to have been conceived of and constructed.

    • Well I’m sorry to hear you don’t like it. I will agree with you that perhaps it has no reason for existing in a typical setting, however there are a few exceptions as you mentioned. I do play D&D to have fun though, and sometimes fun takes precedence over plausibility, at least in my book. So sure it might be wonky, but I play to have fun and fun can come in all forms be it a heavy hearted campaign or a silly romp through a fantasy setting.

      PS: Congrats on posting the first ever blatantly negative comment on my blog, I have earned a new achievement IRL.

      • But plausibility is actually relevant in this case. You’ve set it up so that the effects are subtle, and there’s effectively a mystery aspect to the players figuring out what’s going on and where the problem came from. A mystery is only engaging if adequate clues are provided and the solution makes sense– so in other words, if it’s possible for someone to solve it. This mystery has major roadblocks to being solved, because the solution is incredibly unintuitive.

        First of all, you’re expecting people to dig into their knowledge of extremely obscure real-life medical conditions to figure out what’s going on. When most people sit down to play a fantasy game, they turn off the “real world” parts of their brains because concepts like “dungeon’s far away? Hop into a helicopter!” and “Disease spreading? Quick, kill all the rats and boil your drinking water!” break the immersion of the setting. You’re asking people to re-activate those parts of their brains, which is essentially asking them to break their own immersion in your fantasy world. Think about how much “fun” it would be if the trap was a less exotic type of disease– “Aha! That poison gas gave us all genital herpes!”. Sure, your players know what that is and could probably diagnose it given adequate clues, but there’s no reason for their *characters* to have that information.

        Implausibility is the other major roadblock, which I covered above. Combined together, these two problem add up to a major problem in the mystery-solving process- even if your players think of the correct solution, they’re going to dismiss it because it doesn’t make sense in context. They’ll dismiss DMS as what’s going on (unless you Deus Ex Shoehorn the explanation into an NPC’s mouth or an awkward knowledge check) because it’s not appropriate character knowledge, and they likely won’t figure out that it was caused by the gas because such a trap makes no sense. They’ll think of those two parts of the solution, realize they’re incredibly unlikely explanations, and move on to other theories.

        Then later when it turns out that their theory was correct, they won’t feel satisfied that they were right; they’ll feel confused. Instead of “AHA!”, you’ll be greeted by “Wait… really?”

        Which brings us back to the first paragraph– a mystery is only engaging if the players can actually solve it, and this mystery is inherently resistant to being solved because the solution requires a combination of out-of-character metaknowledge (like if your dungeon door required the Barbarian and Thief to calculate an Eigenvalue to be opened) and isn’t consistent with what a denizen of fantasy world would do (which would be to guard valuable treasure with traps that KILL THE THIEVES, thus keeping the treasure in the vault where you left it).

        • The article was written with an entirely open ended format, there doesn’t have to be a some sort of unsolvable mystery if you set it up with the right context. It doesn’t have to literally be a trap, although it could be entirely solvable and feasible within a given game world (with obvious parameters considered).

          The cause and effect of this “trap” is just a means to an end, and meta game information isn’t assumed to be required or known in any way, the “trap” is simply modeled from a real life condition. I’m not assuming my players or their characters to have any knowledge of it, nor should they. It would make for a good curse mechanic or legend of sorts, I’ve already gotten one commenter who’s posted a perfectly good example of such. The DMS trap was not meant to be thought of in a literal sense, perhaps it came off that way?

          Listen, I’m not going to over intellectualize the trap, nor RPG’s as a whole and dissect this further. I play this game to have fun, I also don’t find myself hard pressed for stone cold logic in a world where people throw fire from their fingertips and build elaborate subterranean mazes to safeguard their valuables.

          I’m sorry this has bothered you so, hopefully next weeks writeup from Sersa V will suit your style a bit better, then again perhaps not? I’ll be somewhat anxious to see what you think. 🙂

  2. Awesome! I like the whole One of these things is not like the other/ “I bet its Roger the Rogue. “Lies Fiddles you lieing gnome lock!!”

    Again well done and excellent read.

  3. I tweeted this to you, but figured I’d post it here, too:

    I could see the trap as a curse. Maybe the PCs defeat a witch and she curses them with DMS. They laugh off her words, but then doubts start forming. They start acting weird. Maybe so-n-so was cursed, but I’m fine. That shop keeper looked at me funny, maybe it is me. Why did so-n-so touch his sword just then?

    Maybe it isn’t really a curse. Maybe it is all in their heads. Or is it?

    • That’s a great example of being able to put this “trap” into effect in a more plausible way. The mechanic as to how it happens isn’t nearly as important as the end result ensuing, it’s just a means to an end really.

  4. I’m with Lotofsnow on this one- this sounds like a great Curse..

    When reading it I was instantly imagining characters pissing on some sort of fey being… A hag, or a satyr…

  5. I personally think it would be one last great F you to anyone that topples the boss. I’ve setup similar things, basically if the boss dies / gets defeated he has one last screw you to whoever kills him. But mine have been petty – Belt of Masculinity / Femininity who’s dweomer has been altered to appear that of Giant’s Strength. Crap like that….

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