How to design a quality trap
How to design a quality trap

How to design a quality trap

Designing Quality Traps


This article will teach you how to turn traps into exciting encounters on their own. In my last article, Problems with traps, I discussed some of the problems traps cause in RPGs and then came up with a list of things traps need to do to become exciting encounters by themselves.

A good trap needs to:

  1. Feel fair
  2. Not be based only on luck or a single die roll
  3. Not slow down the game with dice rolls
  4. Have more than one part
  5. Give the players something to solve
  6. Rely party on character skills/abilities

Solving a trap should be part player decision making, part character build, and part luck… usually in that order.


There are six steps to designing a trap as an encounter. While this process may seem complected and tedious the first time, with practice, many of the steps can be done quickly or on the fly. However this article will look at each step so that anyone learning won’t miss what might be common sense to an experienced DM.

Step 1: Give the trap a purpose

It is not enough to write, “spike trap”. Answering some of the following questions will help you ground your trap into the reality of your game, making it more logically consistent so that your players can begin to spot patterns.

Ask yourself:
Who made it?
Who was it made to stop?
What kind of trap best suits this location?
How do the traps creators avoid triggering it?
Has the trap been triggered before?
Why use this trap at this location?

Step 2: Design trap components and solutions

By thinking about the mechanics of a trap, we are making them more fair, less based on luck, less based on single dice rolls, adding multiple parts, and offering players more decisions for solving the puzzle all in one step.

What triggers this trap?
What does the trap do when triggered?
How is the trigger connected to the mechanism?
What is needed to hide this trap?
What magic is used for this trap? (if arcane)
What are some likely ways to “solve” this trap? (avoid, disarm, safely trigger)

After completing this step you will stop having “poison trapped chests”, and start understanding the mechanics of how these traps actually work. A “poison trapped chest” could be anything from a needle, to a glass vile that breaks when opened. If you don’t know which mechanism the trap is, how can you know what happens when one of the players kicks the chest really hard? Does that set off the trap? It would have no affect on the needle, but might shatter the vile. Having a “poison trap” is equivalent to having the PCs fight “a big monster”. If you don’t know what the monster is, how can the players effectively fight it? If you don’t know what the trap is, how can your players effectively disarm it?

Step 3: Identify starting clues

DM: you walk into a long, rectangular room and see a large statue sitting on the other end of the room 100 feet away.

Player: I want to look around the room but not go near the statue yet.

DM: you step into the room onto a large tile with a dragon carved on it. The tile sinks down and fire shoots out of it, engulfing you in flame.

Player: you didn’t tell me there was a massive tile with a dragon carved in it.

DM: that would have given it away. You didn’t roll a perception check.


As a DM it’s important to remember your players can only see what you explicitly tell them. While it might be more realistic to have “gotcha!:” traps hidden away, players cant search your head for clues. This is what causes players to roll hundreds of needless perception checks and stalls out the game as the characters literally crawl through the dungeon searching every square for clues.

The way to solve this is by building trust with our players. Whenever there are traps, I will provide my players with a clue that the trap is there. This way, even if they do trigger the trap, they can put together the clues and realize their mistake, while still trusting the DM to give them more clues before the next trap. As a DM I want my players to know they don’t need to search every square inch of every room in the five miles of tunnels. I will provide them with at least some indication that will narrow it down to a smaller area for them.

Here are seven types of clues you can give to alert your players of traps:

  1. sensory cue
    Use one or more of the five senses to alert the players to possible danger: sight, touch, smell, sound, or taste.
  2. Pre-triggered
    Show a trap that has already been triggered to allow the party to extrapolate clues to look for when they encounter a live trap.
  3. Emerging pattern
    Show a series of trap types, trap placements, or other trap clues that build a pattern for the party to recognize. For example the smell of sulfur near any fire based trap in a dungeon builds up their sense of fear and awareness whenever they smell it.
  4. Common trope
    The secret door into the thieves guild, a gold chest on an alter, a scroll case found on an assassins body… these my be areas where you don’t have to give as many clues because fantasy culture has built into our heads that these things are always trapped. If the party doesn’t check a chest on the altar for traps, they will feel stupid rather than confused when the trap goes off.
  5. 6th sense
    This can be any other sensory cue a character in a fantasy setting might have. A wizard might sense magic or a dwarf might get a gut feeling something is off about the stone structure.
  6. Told or shown trap location
    A trapped room might be marked on a map or the characters might be warned of a trap by an NPC.
  7. Show one trap component
    Showing the party half of a trap, like a ceiling full of spikes, leaves the party wondering where the trigger is. Showing the party a trip wire leaves them wondering what it triggers. Both provide exciting interactions as the party investigates to find the rest of the trap.
Step 4: Identify skill checks

After shifting some of the responsibility of finding and solving traps to the players by not making them rely only on perception checks and thieves tools checks, we have to make sure that the rogue still feels rewarded for the skills he has chosen.

Come up with a list of skills that can be used to get information about the trap and how it functions. This process becomes part of the puzzle. Using skill checks to figure out information about the trap, how it functions, and how to disarm it is a major part of the engagement in solving traps.

Step 5: Increase difficulty

Instead of thinking of each trap as an individual, stand alone puzzle, you can think of every trap in an entire dungeon as one giant puzzle with multiple parts. This mindset allows you to give away a few traps to provide clues and build foreshadowing and suspense for future traps. If you have ten traps in a dungeon, you might have the first two be already triggered by previous adventurers so that your party can get some clues and learn a bit about how the trap functions. Then you can increase the difficulty of the traps throughout the dungeon, hopefully building in a gradual difficulty progression. Here area few ways to make traps more difficult:

Remove a clue (keep a minimum of one)
Take away a sense (darkness prevents them from seeing the trap for example)
Prevent the most obvious solution (a pit trap too long to jump over)
Add a time limit (room filling with water)
Add an additional problem or distraction (combat)


To recap. The steps to designing a quality trap are:

  1. Give the trap a purpose
  2. Design the trap components and solutions
  3. Identify your starting clues
  4. Identify skill checks
  5. Increase difficulty

Running quality traps

By now you have a well planned out trap complete with a purpose for being there, multiple parts, and some planned skill checks to help them solve it. Now you have to insert the trap into the game and run it.

Step 1: Give starting clues.

For the trap to be an encounter, players have to have at least one of the clues to start with. Thy have to have some idea that this is a place that might be trapped. Many GMs skip this step because they didn’t give their traps any parts or complexity, so they are afraid that giving clues will instantly ruin the trap. Once you’ve followed the steps above though, you can give multiple clues without ruining the fun of your trap.

Step 2: Find other ways to interact with traps.

Since the approach of clues means that some traps will be triggered less often (thought this isn’t necessarily true if you plan them well) or that some traps will be triggered before the party gets there, we can now use them in different ways in the game. Luckily, the design of our traps makes them more exciting even when the characters don’t blunder into them. Here are a few ideas of ways to interact with traps even after the players have figured out how they work.

  • An enemy can trigger the trap
  • Players can reset or re-purpose the trap
  • Players can attempt  to disable the trap
  • Distractions can cause the players to not be able to disarm a trap even when they know how it works
Step 3: Adjust difficulty.

The last step is to adjust the difficulty of the traps in your game. If your players are still blundering into every trap, make sure you are giving enough starting clues and perhaps make them more obvious. If the party is skilled at finding and disarming all of your traps then you might bump up the difficulty by doing the opposite.

In the next article I’ll give examples of how to use this process to turn several “gotcha” traps from published adventures into encounter traps that feel more fair. Then we will build an entire trap from scratch.

Here’s the link to the last article in this series.

Trap examples



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