Traps, Assassins, and Using Passive Perception

[mr_odd]

So, in the lethality of 5e thread, an interesting question came up: when do you use passive perception, and when do you actually roll?

I have been Dm-ing that passive perception is "always on" while players would roll anytime they are actively looking for something. How do you run perception, and does it change for the situation? Vs. hide checks, vs. traps, and vs. secret doors are all different situations that could be handled differently.

[Kyutaru]

I do it kind of like spot checks. If they're about to pass a secret door or trap, I have them "spot check". Failure means they triggered the trap, success means they saw it just in time. Assassins are the same, clearly you are about to get stabbed. Make a spot check to see if you noticed his presence before that actually happens.

[mr_odd]

I do it kind of like spot checks. If they're about to pass a secret door or trap, I have them "spot check". Failure means they triggered the trap, success means they saw it just in time. Assassins are the same, clearly you are about to get stabbed. Make a spot check to see if you noticed his presence before that actually happens.

So what role does passive perception play in your games?

[GiantOctopodes]

So, in the lethality of 5e thread, an interesting question came up: when do you use passive perception, and when do you actually roll?

I have been Dm-ing that passive perception is "always on" while players would roll anytime they are actively looking for something. How do you run perception, and does it change for the situation? Vs. hide checks, vs. traps, and vs. secret doors are all different situations that could be handled differently.

Indeed, exactly as described. Unless the players in question are obviously distracted with things and clearly oblivious (arguing fiercely with an npc as they advance through a dungeon, researching something in a book as they're walking, struggling to control an unruly prisoner, that kind of thing) passive perception is always going. Traps and assassins are contested by passive perception.

When players declare "I look for" or "I search" or otherwise imply they actively wish to engage in the art of perception, they roll. Sure, they could say that at the beginning of every hallway, but two things to remember:
1) It will even out anyway. There is no actual benefit to them doing so in the long run, the average will equal their passive perception.
2) If you declare you're looking for something, you must be specific! Saying "I search for traps" should prompt an "ok, where do you look?" response, and if they are searching the walls, floors, and ceilings, they have no chance to find that proximity mine style explosive trap inside the barrel sitting there (though you're a bad and evil DM if you don't at least mention the barrel to them in your description of the hallway, just saying). Saying "I search for assassins" means nothing! Where do you search?

The Alert feat lets someone be much more observant at all times (essentially giving them advantage on their passive perception, but also stacking with advantage) and allowing players to use active vs passive perception in places they haven't actively declared to you an interest in perceiving something diminishes the value of that feat.

[Shadow]

I have been Dm-ing that passive perception is "always on" while players would roll anytime they are actively looking for something.

That's how I work it, except in my games any roll for perception lower than 10 on the die becomes 10.
That means the players' passive perception is the minimum roll. If they roll lower, they use their passive. Because passive basically means what the can notice when not even trying, so when they are actually trying they can't do worse.

[Tenmujiin]

That's how I work it, except in my games any roll for perception lower than 10 on the die becomes 10.
That means the players' passive perception is the minimum roll. If they roll lower, they use their passive. Because passive basically means what the can notice when not even trying, so when they are actually trying they can't do worse.

Given that passive perception is always on this is basically how the rules work anyway since if you miss something due to your die roll being lower than 10 your passive perception should pick it up anyway.

[mr_odd]

That's how I work it, except in my games any roll for perception lower than 10 on the die becomes 10.
That means the players' passive perception is the minimum roll. If they roll lower, they use their passive. Because passive basically means what the can notice when not even trying, so when they are actually trying they can't do worse.

See, here's the thing though, I don't do that, and here's why: when you're actively looking for something, some times it makes it harder to find. In real life, I am terrible at looking for things. I will place something down then completely forget where I put it. If I actively look for it, it will take me forever, but if I just leave it, I'll see it out of the corner of my eye at some point.

[Kyutaru]

So what role does passive perception play in your games?

Noticing stuff that isn't about to kill you.

[Ghost Nappa]

Is a player consciously choosing to examine the world around them for something suspicious?

Yes: Have them roll.
No: Use their Passive.

[Person_Man]

I swing back and forth on this issue. Currently, I rarely use passive checks.

Instead, I describe the setting/room to the players. then they describe what they want to do. Based on their choice of how to proceed through or search the room and the type(s) of traps in the room, I set a DC(s) for how difficult it is for them to notice any trap(s). I roll once for the entire party behind a screen, and if the player with the highest Perception and/or Investigation Skill (I combine them in my game, players can use Int or Wis for either Skill) has a roll that's equal to or higher then the DC(s) I set, they notice it. Otherwise, the natural consequences of their actions occur, which may or may not set off the trap, depending on what it is and what they do.

In my opinion, there is no point to putting a trap in a dungeon or whatever if you know for sure that players are going to find it with a passive check of some kind. It basically just slows down the game, and has little to no ability to create drama or an interesting experience.

[Demonic Spoon]

The above is my feeling on the matter. I use passive checks basically just for stealth or other occasions where there is an opposed d20 roll. If you want to use passive perception, then I'd make the passive DC 5 higher than the active DC, and manipulate the DC based on the players' actions.

[JFahy]

In my opinion, there is no point to putting a trap in a dungeon or whatever if you know for sure that players are going to find it with a passive check of some kind. It basically just slows down the game, and has little to no ability to create drama or an interesting experience.

You can still create a sense of danger with a trap if the party finds it,
and my group will move heaven and earth to use a found trap against
the bad guys. :smallsmile: It also makes sense - bad guys aren't going
to quit placing a DC 13 traps, worldwide, just because your group has a
scout with 16 wisdom.

It also affects the party's behavior in potentially interesting ways,
especially if the perception guy is distracted and disabled so somebody
else has to take point - and of course, not every trap has to have the
same DC. Some can be easy passives, some can be 'only their best
guy will find this in time and only if he's on point', and some can be
tricky enough that nobody's finding it without doing an active search
in the right area.

[GiantOctopodes]

You can still create a sense of danger with a trap if the party finds it,
and my group will move heaven and earth to use a found trap against
the bad guys. :smallsmile: It also makes sense - bad guys aren't going
to quit placing a DC 13 traps, worldwide, just because your group has a
scout with 16 wisdom.

It also affects the party's behavior in potentially interesting ways,
especially if the perception guy is distracted and disabled so somebody
else has to take point - and of course, not every trap has to have the
same DC. Some can be easy passives, some can be 'only their best
guy will find this in time and only if he's on point', and some can be
tricky enough that nobody's finding it without doing an active search
in the right area.

Agreed. A relatively obvious trap located near the beginning of a dungeon can be a nice, friendly way to flag for your players too that the creatures in question like to use traps, and the change in player psychology once a single trap is found can be, from my experience, absolutely hilarious to behold. Of course the trap they *don't* find at the beginning of the dungeon that cuts the hitpoints of part of the group in half to kick things off can also be a nice way to flag that for your players, albeit not nearly as friendly.

[Louro]

I was the one who asked because I got a player who picked the observant feat, which grants advantage on passive both perception and investigation.
If I switch to make the group rely on active search and rolls then I feel like punishing that player for picking such a good feat. But using passive I know beforehand what te result will be, which I don't like. We discussed this topic last session but didn't reach any satisfying agreement.

Right now we are using the passive scores to notice stealth and other contested rolls, along with some mundane interactions (noticing a thief pick pockets attempt on someone else, someone "performing" the walk pattern of an ally who he is disguised/illusioned as...) as many of you suggested already.

This player's passive is 17, while his active is just d20+2

[mr_odd]

I was the one who asked because I got a player who picked the observant feat, which grants advantage on passive both perception and investigation.
If I switch to make the group rely on active search and rolls then I feel like punishing that player for picking such a good feat. But using passive I know beforehand what te result will be, which I don't like. We discussed this topic last session but didn't reach any satisfying agreement.

Right now we are using the passive scores to notice stealth and other contested rolls, along with some mundane interactions (noticing a thief pick pockets attempt on someone else, someone "performing" the walk pattern of an ally who he is disguised/illusioned as...) as many of you suggested already.

This player's passive is 17, while his active is just d20+2

See that's the thing. With that feat, a level four character can have a passive perception of 20 (+3 Wis, proficiency bonus +2, and the feat +5).

[Socko525]

Thank you for this thread, it comes up quite often in our games

[mr_odd]

I had a similar issue with one of my players last year in 3.5. He did everything he possibly could to max out spot, and always got above 30 on his rolls. Now don't get me wrong, I want a player to be successful at his or her character concept, but there is a difference in always seeing everything, and being pretty good at spotting bad guys and bad things. It frustrated me to no end, because I felt like I could place no traps, or hidden bad guys in a session. It was useless time after time again.

What I may propose as a solution, at least in dungeoneering: When in rank, the only character who uses passive perception is the one in the front. This way, your 20 passive perception character may only be able to be at the front for a while (especially if he is a squishy caster).

[odigity]

That's how I work it, except in my games any roll for perception lower than 10 on the die becomes 10.
That means the players' passive perception is the minimum roll. If they roll lower, they use their passive. Because passive basically means what the can notice when not even trying, so when they are actually trying they can't do worse.


Given that passive perception is always on this is basically how the rules work anyway since if you miss something due to your die roll being lower than 10 your passive perception should pick it up anyway.

You can have a passive perception check lower than 10 if your Wis is 8 or lower...

[Xetheral]

I had a similar issue with one of my players last year in 3.5. He did everything he possibly could to max out spot, and always got above 30 on his rolls. Now don't get me wrong, I want a player to be successful at his or her character concept, but there is a difference in always seeing everything, and being pretty good at spotting bad guys and bad things. It frustrated me to no end, because I felt like I could place no traps, or hidden bad guys in a session. It was useless time after time again.

Actually, I find knowing that a character is going to succeed all their spot checks makes adventure planning a LOT easier, because you don't need to prepare for multiple contingencies. Plenty of traps are interesting obstacles even when you know they're there, and spotting the hidden opponents means you can reliably plan out a battle assuming the PCs will ambush the ambushers.

Here's an example trap that's MORE fun if the party notices it:

The party encounters a stone door in an old tomb, sealed tight with mortar. They chip away the mortar and open the door, only to discover that somehow the air pressure was a LOT lower on the other side. The air from the hallway rushes into the room, disturbing a very fine powder that blows everywhere and makes people cough. The perceptive character makes an impossible-difficulty perception check and hears a faint clicking noise over the airflow, which leads her to a strange clockwork contraption connected to a vial. The party then gets to choose whether to break the mechanism (i.e. disable it) immediately, or try and figure out what it does. If they study it, they discover that it is some sort of timer device apparently started when it was disturbed by the wind, and that it's going to result in a small hammer breaking the vial right about... now. The alchemist's fire in the vial ignites spontaneously upon contact with oxygen, which in turn ignites the air in the room now thoroughly saturated with highly-explosive cooking flour. I believe that's some fire damage and a fort save to avoid the effects of suffocation long enough for the oxygen in the tomb to be replaced from outside....

If such a trap wasn't noticed, it would be much less fun since it would be virtually impossible to avoid otherwise. As it is, if the party disables it first and investigates later, they get to laugh in relief at having narrowly avoided a fuel-air explosion in a confined space. If they chose to be cautious and investigate first, they get to laugh both at how for once recklessness would have been wise, and also that they're so badass they (probably) just survived that same fuel-air explosion.

[Louro]

Nice trap, a bit difficult to build but funny.

How to overcome outrageous spot scores? Add stuff there is no way for him to spot. Invisible assassin, assassin hide behind an illusion, trap inside a barrel or below a book...
These are not impossible situations, you could figure out the invisible with investigation maybe, you can save the illusion, you can search the book before touching it...
This way you bypass the spot (passive perception) roll with other rolls or RP. Of course, this is just situational, if a player wants to be aware and invests into it he should succeed there, but not all the time.

Add the secret door trap. A secret door which is actually a trap, which you can only be noticed with investigation since there is nothing extrange you can see at first glance.

[Spacehamster]

The character I'm building will end up with 29 passive investigation and 31 passive perception at max level if we get there. :) and on topic we use passive whenever players are not actively looking.

Bit off topic but if 1 person in party ends up seeing an ambush just before it strikes, does that make just him not getting surprised but rest of party still get surprised?

[mr_odd]

The character I'm building will end up with 29 passive investigation and 31 passive perception at max level if we get there. :) and on topic we use passive whenever players are not actively looking.

Bit off topic but if 1 person in party ends up seeing an ambush just before it strikes, does that make just him not getting surprised but rest of party still get surprised?

That's a DM call. I'd say yes and no, depending on the situation and if they have time to alert the other members.