On the Thursday Trick, Vents, Sprays, and Agency

Vents & Sprays (Vents/Sprays)

Trigger: Varies Effects: Multiple Targets, Never Misses
Save:WandsDuration: Instant
Resets: AutomaticBypass: Avoid

Description: These traps are characterized by a variety of factors that separate them from spells or ranged attack traps. First, they often involved gasses or liquids and because they are often sprayed out over a large area they have the property of never missing.

In some cases there is also an onset delay. This means these traps can be triggered and the effect happen in a certain amount of time (sprinklers in a room) or a delay before the substance affects the characters (such as a room filling with water.

Examples of the things that might be vented or sprayed included slime, shrapnel, cold, acid, boiling water, flaming oil/tar, sewage, mummy dust, poison, fire, magma, smoke, methane, sand, steam, sulphur, and water.

If a to hit roll is required it will always ignore armor, but not necessarily shield bonuses. Saving throws may apply given the circumstance. Rods, Staves and Wands is the traditional saving throw for such attacks, allowing half damage or to avoid instant death.

Detection: These traps can be both the best kinds of traps, and the worst kinds of traps. Because they often have extremely negative properties, they can be ran in such a way where they are just Gotcha! traps, causing death or massive damage very quickly. However, this is an extremely poor way to run such traps, for several reasons. None of the vents and sprays above will be able to remove signs of their presence. Some examples
  • Slime will leave a slick slimy coating on the walls and floor
  • Shrapnel will leave gouges and scars in the walls and floor and ceilings
  • Cold vents and sprays may show some signs of their presence due to temperature differences,  areas where the cold strikes repeated may show cracking, the growth of natural molds and fungi may be retarded. If the trap is triggered often or recently, there may be frost, ice or water on surfaces. If it has been triggered somewhat recently, the water will affect the appearance of the walls (they will be cleaner).
  • Acid will leave pits and scarring on whatever surface it is sprayed on. There may be a scent, or the players eyes may start to become irritated.
  • Boiling water may show up due to temperature differences, and will generally insure a sparkling clean area where the walls and floor are blasted with it.
  • Flaming oil and tar will generally cover the upper walls and ceiling with black soot, and the floor may appear greasy or covered in scorch marks. Tar will stick to a surface and blacken and harden under high heat. The hallway may carry a scent of burning tar.
  • Sewage will smell overpoweringly terrible, unless it is stored behind water (like in a toilet) or behind an air tight valve or door.  There will still be an odor because it will be triggered occasionally filling an area with filth. There may be an unusually high amount of mold or spores or other type things in the area due to the rich food source the filth provides.
  • Mummy Dust may leave a coating of dust on surfaces, cause a musty spell, and their may be corpses in the hallway.
  • If a poison is being used in a spray, it most likely is fairly virulent, and therefore their should be corpses, either dessicated in a forgotten dungeon like a tomb, or bones or signs of being dragged off in a more active area.
  • If fire is being vented out, then on the surface that the fire is across from there will certainly be burn or scorch marks. Their may also be burnt corpses.
  • Magma if sprayed or vented out, will melt and re-solidify, causing whatever surface the magma contacts to deform. Areas where magma is sprayed will bubble, twist, buckle, and bulge from the constant melting and re-hardening. Bones and various other mineral items (armor and such) may be embedded in seeming solid surfaces.
  • Smoke will often linger for far longer then it takes to dissipate, leaving a smell for 60' to 100' from the location of the trap for days.
  • Methane is a very dangerous trap, relying on the players flaming light to trigger an explosion. There are several things to keep in mind with methane. First, it is odorless, the natural gas smell you are familiar with is a modern additive to help detect leaks. Second, it displaces oxygen, so even if the entire party has some means of seeing in the dark, it can rapidly cause asphyxiation. Use the rules for how long characters can hold their breaths unprepared for the length of time they can stay conscious.
  • Sand will both collect on the floor (and in clothes, armor, food, despite the best intentions). The first notice the adventurers will have will likely be the sound of sand crunching under their feet. Any surfaces subject to a spray of sand will likely be scrubbed clean. Repeated sand blastings will scour a surface clean, but will also remove the top layer, exposing rougher rock or metal beneath. Sometimes this will be used to fill a sealed chamber, in which case sand coated corpses will often be discovered.
  • Steam is going to insure that whatever surfaces the steam hits are clean, except for the bits of boiled flesh that it removes from it's targets. Do not forget to continue to apply damage as heat metal for people caught in steam wearing metal armor.
  • Sulfur is an interesting compound, either acidic causing burns, or a fine dust causing explosions, or a gas, causing choking and irritation. It is also known as brimstone. The primary method of detection is it's overpowering rotten eggs smell, which is natural.
  • Water is often not sprayed on people for damage, but more often is used to fill a sealed chamber trapping and drowning whoever is within. Water traps often leave water marks, as the fluid removes dirt and grime from surfaces and deposits it on a line along the wall. It also can have a briny or salty smell.
Do not forget that the vents and sprays also must come from somewhere. Nozzles, slots, slats or shutters will be visible places where the substances are expelled.


  1. I'm sorry, I'm going to play devil's advocate here a moment, I hope you don't think I'm trolling, it's just the old Ogre won't lie down.

    This post seems to be about how to steer players toward a safe path through a set of otherwise deadly and potentially undetectable traps. It looks to me like a follow up to your recent thoughts about promoting player agency - all the players have to do is listen really hard to your description and pick up on the floor scratches.

    But that's not just presenting the world and letting the chips fall where they may, it's a kind of Agatha Christie puzzle game. I would contend that it's actively leading the players toward a particular kind of adversarial game experience - it adds "inspect floor" as a continuous action to the PCs' (and maybe players') task list. It's how we ended up with 10' poles and all that jazz.

    I don't have any suggestions for solutions, nor am I going to say "this is bad": traps are puzzles are a kind of game some folks like and traditional in the medium and so on. These are good ideas for signaling potentially deadly traps and avoiding save or die situations. But this sort of design isn't giving the players agency, it's involving them in a tactical minigame - one which runs continuously under the actual roleplaying bit and threatens to interrupt it at any moment.

  2. @Richard

    Hi! You may notice a little 30 page .pdf on the side I wrote called "Tricks, Empty Rooms, and Basic Trap Design"!

    Your comments show a basic ignorance of the structure of an old school game, and I'm glad you brought them up so I could address them.

    The vast majority of rooms inside any structure the adventurers explore are empty. I play first edition so a full 60% of the rooms that the players encounter contain no monster, no treasure, no trap, and no trick.

    In any given encounter, details of the room are given, and at no point do the players know if any of the above are present! Often monsters are noticed first, but not always depending on the beast.

    Each room (or hallway or stairway) is just that and there are a great many details that are given to the player. It is the skill of the player who takes all of this vague information and turns it into whether his character knows it's an empty room, automatically bypasses the encounter, gets a saving throw, or unconditionally is insta-killed.

    This process is described, at length, in the 1st edition Dungeon Masters Guide written by Gary Gygax, as well as covered in many other old school games in truncated form. There are many blogs with indepth analysis of the original works. I recommended any of the blogs on my sidebar for reference, but in particular, Delta's D&D; Rolls, Rules & Roles; and The Alexandrian should be helpful in this regard.

    It is difficult to come up with lots of room descriptions. As wonderful as the extensive tables and advice in the DMG were, I wanted a more in depth assistance with creating the many many empty rooms the players encounter.

    Your assumption that the players are being steered towards a safe path assumes that this is the only information being handed out, when in fact this information is given in the context of the tricks and traps document and is actually a way to offhandedly mention the danger present without giving away the nature of the trap.

    And yes. In a dungeon, once past the threshold into the mythic underworld, I do expect continuous action on the part of the PC's. This is part of them roleplaying - they are taking the role of adventurers in a dangerous situation. And this role they are taking doesn't depend on dice, but their skill as a player. They are free to not use that continuous action or personal skill and possibly, with saves and various other stuff, will survive for a long time.

    But not forever.

  3. basic ignorance
    I had to smile at this. It's true, I've never played an old school game - I was there first time around (or second, perhaps: B/X and 1e, not OD&D) and I took Gary's advice to heart, to make the game my own and do as I would with it. As a result I found a lot of the dungeon stocking advice extraneous to the particular kind of fun we were having.

    As I mentioned in my previous comment, I'm playing devil's advocate here (hopefully politely): I think there's an unresolved philosophical issue going on, that's to do with player agency and what it consists of. I'd say the shining example of player agency is free choice among multiple valid options: the sort of choice you have when you look over a map and say "where shall we go now?" Alexis' much-discussed mustard farming example also falls here: the PCs have a world and must make their own way in it.

    The puzzle game you're presenting here, no matter how far submerged it may be in other stuff, is a willing engagement between players and DM in something else - a more scripted encounter (sorry if I'm misusing jargon here). here's what I mean: there are hazards in the environment. The players must identify them from hints you drop and expand those hints through enquiry, then come up with some solution to the problem once understood. The point at which they make meaningful/free decisions is in solving the problem after identification, but all the hinting and asking you describe in the post is really built on false choices: you can understand/get the right information or fail to do so. And that, in particular, seemed a curious direction to take the player agency noodling.

  4. The point at which they make meaningful/free decisions is in solving the problem after identification, but all the hinting and asking you describe in the post is really built on false choices:you can understand/get the right information or fail to do so.

    I am not understanding how this is a false choice.

    I'm currently running a multi-DM hexcrawl. There are like 20 adventuring sites in the hex north of town. There is a board with city, wilderness, and dungeon quests on it. There is a living world. The players go anywhere they want. They have an encounter. It's in an environment.

    Once they hit that encounter, I describe the environment.

    If it's a trap, there will be clues to the trap.
    If there's a monster they will see signs or a reaction roll will be made.
    If it's a trick, there will be clues to the trick.
    If there's treasure, it may be hidden. It may require some work to get it back to town.
    If it's an empty room, there will be a variety of things there, just like one of the other encounters.

    All of these will involve hinting and discovery and player skill. How is helping people learn techniques to describe things to make traps more interesting than the ars ludi 'bad trap' making a false choice?

    Once they reach an encounter - one that they've choosen freely, they still have mutiple valid options. These traps are no different from kicking in the door and seeing an ogre ahead. They can fight the ogre or run. They can examine the various things in the room (which is probably empty) or leave.

    If by 'scripted encounter' you mean 'adjudicating the worlds response to the actions of the players', then I guess yes, I am enforcing the consequences of their choices - isn't that agency?

    there are hazards in the environment. The players must identify them from hints you drop and expand those hints through inquiry, then come up with some solution to the problem once understood.

    This is role playing, no? You can replace hazards with 'treasure' 'empty rooms' 'monsters' 'NPC's with goals in opposition to the party' etc.

    The assumption that the only information they can receive is verbal is false. There are many dead henchmen corpses that can attest to that. They can make a variety of choices when engaged with the encounter to acquire more information, allowing them to solve the problem.

    I guess I identify what you call 'scripted encounter' and 'false choice' as 'playing D&D'

  5. Awesome. Where'd you get the pictures?

  6. I typed in 'methane explosion' and that's what came up. Impressive, no?

  7. Sure it's all playing D&D - D&D contains a bunch of different kinds of activities (eg. combat, exploration, resource management, social interaction, politics, puzzles), which is one reason it tends to be so different from one table to the next. And I'm not complaining about that in the slightest. These different activities involve different levels of interactivity and agency, though.

    Both you and Zak have stated that players have to be informed to possess agency (yes, of course): here you state an interactive process (question/answer regarding the environment, based on careful attention to the DM's initial description) they can use to get informed. Fine.

    I was just pointing out (as devil's advocate) that this sort of interaction in particular doesn't address player agency much: it's a means to eventually getting some, but the structure of the means is basically similar to that of an exam or a murder mystery: there are clues, the players must draw the correct conclusions, and their reward for doing so is agency: the information they need to be able to manipulate the trap to their own ends. If they fail to get the reward, then in the cases detailed in your post they're likely to suffer the effects of the vent/spray - pretty clearly something they wouldn't choose.

    The false choice I wrote about was the "choice" to get it wrong - to misinterpret or fail to pick up on the clues, like the wrong answers on a multiple choice quiz are "false choices." By "scripted encounter" I meant some situation which will respond in particular, repeatable ways to particular player inputs, such that the players can learn to predict what it will do if they do whatever specific action - a finite state machine, if you want to get fancy. If a puzzle is a finite state machine and certain states lead to failed outcomes then they represent "false choices."

    On a broad definition of role playing all of this does indeed qualify: RPGs often contain puzzles. I tend to reserve "role playing" for that part of the game that involves improv acting or imagining oneself in a specific role in the gameworld, but I'm not dogmatic about it.

    Again, I'm not saying any of what you're doing is bad, nor am I accusing you of limiting player agency. I look forward to reading your document.

  8. These different activities involve different levels of interactivity and agency, though.

    I'm sensing a truistic statement here.

    Your argument (choice is being removed) applies to all activities the players choose to engage in.

    If the players are in combat, they are subject to random rolls. In politics, they are subject to the wealth and current balance of power of NPC's. In a trick, they are subject to the design of the trick. The agency is of course, they can go elsewhere if they wish. The 'false choice' you mention in the trick above, is the same 'false choice' of a player not using fire to kill a troll.

    How does this series relate to player agency? Most DM's play traps as a simple roll - you make your % roll and find the trap or not. That's just an arbitrary penalty.

    This describing of traps and developing the vocabulary moves it from the realm of an arbitrary result based off character skill, and moves it into a discussion on how best to make it rely on player skill.

    This is a boon to role-playing (i.e. taking a role) not only because it helps immersion, but because the traps exist in objective reality and work in a specific, measurable, understandable way, allowing players to solve it however they personalities dictate that they solve the problem.

    also: righty-o

    As an aside, my entire game world is like a very dangerous solid state machine. ;-p

  9. Richard,

    But indeed the choices still involve player agency. You're thinking that the evidence of the trap is the ONLY clue that the characters find. If there are other clues, evidence of treasure or monsters that might have treasure, then the players must weigh the evidence and risks.

    There is a context to the puzzle game of the trap evidence. Not only the other evidence of other features, but the resource game of hit points, torches, oil and the desires of the players. They may suspect that treasure in a tomb will be trapped. Then they may even seek out traps, though of course they will seek to disable or set them off safely.

    With these additional choices and motivations, can you see why we call this roleplaying?

  10. I think the discussion on traps is going about the issue backwards. If the PCs enter a room with a trap, there will be visual signs. It is not like the GM is deliberately adding the phrase "there are patches of rougher than usual rock above the pool" just as a clue to help the PCs. He is doing it in response to a player question "what do I see above the pool", and the response is simply an observation of what you would see above a pool of constantly evaporating toxic acid.

    Where would the bodies of dead previous travelers go? A trap of these types are very resource heavy (where do you get such a supply of magma, for example), so they will not be placed at random areas. They will be in places where people go, and so there will be some remains of people who came before and died. If the dungeon's owner cleans up these bodies regularly, then there is probably a disarming mechanism that is simple enough to use regularly somewhere nearby, etc...

    The players still need to look around, ask questions, and interact with their environment. All that is being said is that these traps do not just exist in a vacuum, and people have the opportunity to use players skill to discover the possible presence of traps.


Related Posts Plugin for WordPress, Blogger...