Search For Traps [Solved, I think]

[Cheesegear]

A room features multiple traps and several secret doors spaced unevenly.
A character declares that they will make a Perception roll, and rolls just fine.

How many traps and secret doors do they find from a single roll?

Only the closest one? Continue making rolls until you don't find something?

Or do they find everything within their field of vision (e.g; Darkvision 60 ft.) that their roll beats the DC of? If you find one trap you find them all?

[MrStabby]

Well they don't declare they are making a perception roll. They declare they are searching for traps, then you ask for a roll as appropriate (I would tend to ask for an investigation check if it was an active search). Then based on where hey described themselves searching, and the result of the roll, you describe what they find.

If they are too broad in their description, ask them to be more specific.

[Cheesegear]

Well they don't declare they are making a perception roll.

You don't play with my players, then.
Players can roll a dice whenever they want. In fact they will roll dice whenever they want. The DM more or less then decides whether or not the roll was pointless because the action they wanted to take didn't require a dice roll.


Then based on where hey described themselves searching, and the result of the roll, you describe what they find.

A 30x30 ft. room contains 36 squares and 24 sections of wall (23, plus the original door to the room). The amount of traps and secret doors in the room can be anywhere from 1 to 59.

In your game a character searches one, 5-ft. square at time, per roll, and finds something or doesn't, per square/section? That's gonna be a lot of dice rolls.

[MrStabby]

A 30x30 ft. room contains 36 squares and 24 sections of wall.

In your game a character searches one, 5-ft. square at time, per roll, and finds something or doesn't, per square/section? That's gonna be a lot of dice rolls.

So for me it would depend on context. And some of it also comes down to adventure design. So if I were building the dungeon, then I would probably stick with a small number of things per room, or at least space them out in terms of DC. If there is a room with a DC 15 and a DC 25 thing to find, I don't mind players getting both on a single check. If they are all DC 15 then I might describe them as a series of traps... but generally I will do it on a room by room basis.

Some exeptions might be if they focus on a specific area (advantage) or if the room is very busy (a lot to check for in different ways).

[Cheesegear]

So if I were building the dungeon, then I would probably stick with a small number of things per room

You didn't design the dungeon. In this dungeon, the room contains countably infinite number of things. The floor is trapped, the walls are trapped, the ceiling is trapped. There are trapdoors in the floor. There are hidey-holes in the ceiling. The are secret exits in the walls. So many things to find!!! So many traps that even the secret doors are traps, and the traps are secret doors!


If they are all DC 15 then I might describe them as a series of traps... but generally I will do it on a room by room basis.

So if there are 10 Traps and 3 Secret Doors in the room, a character standing in the entrance rolls a Perception check of 15 and sees them all using a single dice roll?

[LostBenefit]

A room features multiple traps and several secret doors spaced unevenly.
A character declares that they will make a Perception roll, and rolls just fine.
As others before me have said, the player doesn't decide what they roll for—you do. In addition, it is an investigation, not perception, check to search for traps.


How many traps and secret doors do they find from a single roll?

Only the closest one? Continue making rolls until you don't find something?
I would ask for separate investigation checks for traps and secret doors.


Or do they find everything within their field of vision (e.g; Darkvision 60 ft.) that their roll beats the DC of? If you find one trap you find them all?
You can use their passive investigation against the trap DC while taking into account those with/without darkvision.

[MrStabby]

You didn't design the dungeon. In this dungeon, the room contains countably infinite number of things.



So if there are 10 Traps and 3 Secret Doors in the room, a character standing in the doorway rolls a Perception check of 15 and sees them all using a single dice roll?

Again, it depends on context. Is it a trap on each staue in a room? If so "you observe a series of traps spread accros the statues in the room". If not, then it may be different.

But they won't get anything from standing in the hallway peering out into the room unless its right next to them.

[JNAProductions]

You didn't design the dungeon. In this dungeon, the room contains countably infinite number of things.

So if there are 10 Traps and 3 Secret Doors in the room, a character standing in the doorway rolls a Perception check of 15 and sees them all using a single dice roll?

Sounds like a badly designed dungeon.

Do you have a specific example from a module or play experience, or are you just using hypotheticals?

[KorvinStarmast]

Well they don't declare they are making a perception roll. They declare they are searching for traps, then you ask for a roll as appropriate --snip--
If they are too broad in their description, ask them to be more specific. This is the correct answer.
If there are multiple things to find, ask them to describe where and how they are searching.

You don't play with my players, then.
Players can roll a dice whenever they want. In fact they will roll dice whenever they want. The DM more or less then decides whether or not the roll was pointless because the action they wanted to take didn't require a dice roll. Time for a fresh session zero. Also, advise them that until they read chapter 7 of the PHB, and then discuss how ability checks work with you, there won't be a next session.

If they balk at that, suggest that the next game night you'll all play Risk since they like rolling dice so much. :smallsmile: Or Yahtzee, or Liars' Dice, or ...

[JNAProductions]

Time for a fresh session zero. Also, advise them that until they read chapter 7 of the PHB, and then discuss how ability checks work with you, there won't be a next session.

If they balk at that, suggest that the next game night you'll all play Risk since they like rolling dice so much. :smallsmile: Or Yahtzee, or Liars' Dice, or ...

To be fair, for a Play by Post game, it can save a lot of time if players are active with their rolls, rather than waiting for the DM to call for a roll.

That does come with the caveat that sometimes rolls will be discarded, because it wasn't appropriate for the situation, but given how much momentum is needed in a PbP game... Small price to pay.

[Cheesegear]

But they won't get anything from standing in the hallway peering out into the room unless its right next to them.

Okay great. We're getting somewhere. A character can only search one 5-ft. area around them.

I move 5 ft. Search. Roll dice.
I move another 5 ft. Search. Roll dice.
I move another 5 ft. Search. Roll dice.
I move another 5 ft. Search. Roll dice. Didn't find anything...Oops I triggered a trap.

Easy. Especially with electronic dice where you can just keep hitting the button. Should take less than a minute to find a path through the room, or trigger a trap.


Do you have a specific example from a module or play experience, or are you just using hypotheticals?

...I think I just did.

How many traps can I put in the room? As many as I want. I'm the DM.

Okay, what does that look like? Turns out I just realised it looks a lot like Minesweeper - the players need to find a path from one side of the room, to the other. Every square in the room is potentially trapped - or it isn't, that's what the players have to find out. That's the challenge. It's Minesweeper. Yep. I figured out what I want.

Move 5 ft. at a time, get out your phone and spam Investigation rolls until you fail and move into a square you shouldn't. I think that's the room.


Time for a fresh session zero. Also, advise them that until they read chapter 7 of the PHB, and then discuss how ability checks work with you, there won't be a next session.

Oddly, it saves time. A player rolls a dice without asking the DM:

1. A roll wasn't required. But the same amount of speaking still happened, the same amount of time passed.
2. A roll was required, and now the dice is already rolled without waiting for the DM's permission.
3. A roll was required, but not using the Skill the player thought. The dice has still, already been rolled, they just need to put different modifiers on it.

[JNAProductions]

...I think I just did.

How many traps can I put in the room? As many as I want. I'm the DM.

Okay, what does that look like? Turns out I just realised it looks a lot like Minesweeper - the players need to find a path from one side of the room, to the other. Every square in the room is potentially trapped - or it isn't, that's what the players have to find out. That's the challenge. It's Minesweeper. Yep. I figured out what I want.

Move 5 ft. at a time, get out your phone and spam Investigation rolls until you fail and move into a square you shouldn't. I think that's the room.

That sounds like a really boring room. And also one that would make more sense in a videogame than a TTRPG.

Edit: It's also poorly designed, assuming the traps are even moderately dangerous. If they succeed at finding a trap on a 6+ (75% chance of success) then two traps gives them nearly a 50% chance of failure.
Three traps gives them nearly a 60% chance of failure.
Just shy of 70% for four traps.
More than a 75% chance of failure on five traps.

Note that "failure" there is defined by at least one trap being triggered.

[Cheesegear]

That sounds like a really boring room.

If the party is smart, it should take less than five minutes to get through. I'm not really concerned with a room being boring if it only takes five minutes.


It's also poorly designed, assuming the traps are even moderately dangerous.
[describes the challenge getting harder as you progress through the room]

Sounds to me like it's designed perfectly.

Alright, thread over. I guess. I actually figured out what I want and what the solution looks like in a few posts.

[JNAProductions]

If the party is smart, it should take less than five minutes to get through. I'm not really concerned with a room being boring if it only takes five minutes.

Sounds to me like it's designed perfectly.

Alright, thread over. I guess. I actually figured out what I want and the solution.

I don't think "Roll and hope you roll well" is challenging.
It's rote.

[MrStabby]

That sounds like a really boring room. And also one that would make more sense in a videogame than a TTRPG.

Edit: It's also poorly designed, assuming the traps are even moderately dangerous. If they succeed at finding a trap on a 6+ (75% chance of success) then two traps gives them nearly a 50% chance of failure.
Three traps gives them nearly a 60% chance of failure.
Just shy of 70% for four traps.
More than a 75% chance of failure on five traps.

Note that "failure" there is defined by at least one trap being triggered.

I mean I guess it needn't be boring. What if there is more to it? Sure, if rolling for 20 investigation check is your way through, then it is, but if its also open to other solutions to bypass the traps or safely trigger them from afar or to detect them em masse then it could be a fun challenge with a brute force solution if you don't have any better ideas.

[JNAProductions]

I mean I guess it needn't be boring. What if there is more to it? Sure, if rolling for 20 investigation check is your way through, then it is, but if its also open to other solutions to bypass the traps or safely trigger them from afar or to detect them em masse then it could be a fun challenge with a brute force solution if you don't have any better ideas.

The way Cheese is talking, it sounds like he expects them to just brute force it.

I also don't think that this kind of room really makes sense in most contexts-I'm sure there's some scenario where Minesweeper the room makes sense from an in-world perspective, but I can't think of any off-hand.

[Cheesegear]

I mean I guess it needn't be boring. What if there is more to it? Sure, if rolling for 20 investigation check is your way through, then it is, but if its also open to other solutions to bypass the traps or safely trigger them from afar or to detect them em masse then it could be a fun challenge with a brute force solution if you don't have any better ideas.

Well my first thought is that the Wizard casts Fly and just bypasses the room.
The next character might try to jump 20 ft. into the back end of the room and try to reach the door as fast as possible.

Also, a room described on paper is almost always boring; 'In this dimly lit room there is an Ooze. Defeat it, I guess.'
...But that's not really what a combat, is. Is it?

There are a series of traps on the ground. What do? Maybe you tie a Halfling to a rope and chuck him to every square and pull him back. Maybe you Summon Animals and run them into the room and see what happens. There are lots of solutions to the problem. Sure, the most obvious solution - brute forcing it - is the most boring - but brute forcing solutions usually is boring. That's also the solution that takes the longest in-game time, but consumes the least resources and arguably poses the least risk to the players short of flying.

I've not usually known my players to be safe or boring. But the safe and boring solution does have to exist because players don't have infinite resources, and maybe safe and boring is the correct way. I guess it just depends how much damage the traps do and how scared I can make my players of taking damage.


I also don't think that this kind of room really makes sense in most contexts-I'm sure there's some scenario where Minesweeper the room makes sense from an in-world perspective, but I can't think of any off-hand.

Indiana Jones and and the Last Crusade has a floor full of traps.


My main concern is a question of fairness - not of construction.
If a player finds one trap, but not the other, even though both have the same DC, is that fair?
Turns out, yes. Because Investigation rolls are made one square at a time.

Okay well that sounds awful depending on the size of the room. ...Oh wait phones exist. With dice rollers on. It's actually a very quick room that's mostly just a set of skill challenges and each time you fail one you take damage until you exit the room. I've seen much worse rooms, and much less fair rooms - in published modules, too.

[Greywander]

In pondering this problem, I've come to realize I haven't DMed enough to have a good answer.

YMMV, but it seems like this should use both Perception and Investigation. Perception allows you to notice the tells of traps; things like indents, grooves, tripwires, or uneven floor tiles. Investigation allows you to recognize those as trap components, and even what kind of trap specifically (though the DC for that might be higher).

Passive skills can be a big time save in situations like these. Instead of calling for a roll when they enter each room, simply use your players' passive Perception and Investigation to determine what traps they can see right off the bat, making sure to excluding anything not in direction view (e.g. behind a pillar or other obstacle, around a corner, etc.).

As for how you handle it from there, I think that depends on how heavily you want to lean into traps as a gameplay mechanic. Some tables want to roll once to deal with all traps so they can get on to other things. Others will enjoy creeping around the room meticulously identifying and disarming each individual trap. You could ask the player which parts of the room they're searching and have them map out their path through the room, then roll one Perception check for any traps in that area. If they move through a trap and don't roll high enough to notice it, then the trap goes off, otherwise they avoid it. Based on their roll, feed them both trap tells and red herrings so they don't know which ones are traps and which ones are just set dressing. Then they can investigate each one individually, rolling a separate check for each. Anyway, that's just one example. If I had more experience DMing, then I'd have a better idea if this was actually a good idea or not.

One rule I've heard of that sounds like fun is the "click" rule, which simulates an experienced adventurer's reflexive response to triggering a trap. When a trap is triggered, the DM simply says, "click," to indicate that a trap has been triggered. Each player can then do one thing to try and avoid the trap's effects. The thing is, they don't know what kind of trap it is. If you dive forward, you don't know if you're going to narrowly dodge a pit trap or be jumping face first into a swinging blade. If you raise your shield you might block poison darts, or you might have the floor fall out from under you. If you flatten yourself against the floor you might avoid a gout of flame, or you just get a real good look at the spike trap before it impales you. Depending on the action taken, the player might get advantage or disadvantage on the roll to avoid the trap, or not even need to make a roll.

[Tanarii]

Figure out the time it takes to use passive investigation per section of area, and ask them how much time they're willing to spend.

If they want to take less time they can search less than everything. If they are willing to risk the random encounter checks, they can search more. If they really want to risk the checks, they can even take ten times as long to automatically succeed, per the rules.

I've had groups that moved at 1/10th speed so they automatically find any threats possible to find, and others that don't want to get bled dry by random encounters and settle for passive and normal movement rates. But even the latter will sometimes post a guard to watch for incoming enemies, divide up a room between the rest, and take ten times as long to be sure they've found anything possible to find by.

The rules don't have a specific time to search an area for traps, so you'll have to decide how long you want it be.