Detecting traps

[andylatham82]

Hi,

If PCs are travelling along and a hidden trap is up ahead, a Wisdom (Perception) check is done to see if they spot the trap. Is this check something the DM does so as not to let the players know something is there? Or does the DM ask the players to make the check but just withhold information on why they're doing it until after it's complete?

Thanks!

[DivisibleByZero]

Every DM does it a little differently. Each of your examples are valid.

Personally, I never ask for rolls for something that the players wouldn't know about. I roll it myself (or use passive) unless they specifically tell me that they're looking for X.
That way, they don't even know that they don't know, if you know what I'm trying to say.

[Joe the Rat]

Depends on the setup.

Overland travel, I ask who is watching for trouble (as opposed to navigating or foraging or skinning mules) and have them roll, whether or not there is something there. Roll as you travel becomes a rote event, so actually having something to notice is still a surprise.

Generic: Secret roll.

Alternate system: roll trap vs. passive perception. Trap DC-10 is the "Stealth" roll for the trap to not be seen (think of it as the skill at which the trapsmith hid it). It's sort of analogous to rolling stealth v. PP for ambush situations.

[Naanomi]

I let people use Investigation to find traps, the DC Being higher or lower than it would be perception depending on the nature of the trap (hidden but 'obvious' traps like covered pits, trip wires... easier with perception. Tiny mechanical devices, easier with investigation), usually a 5 DC difference

[Specter]

I use passive perception against the trap DC. If the players move at a normal pace, then they'll have a -5 to that passive score (unless someone has the Dungeon Delver feat). If a guy with that feat moves at a low speed, he would get +5 to that passive score.

But once players figure out that going slower means less traps, you'll need to put some kind of time pressure on them.

[Ghost Nappa]

I use passive perception against the trap DC. If the players move at a normal pace, then they'll have a -5 to that passive score (unless someone has the Dungeon Delver feat). If a guy with that feat moves at a low speed, he would get +5 to that passive score.

But once players figure out that going slower means less traps, you'll need to put some kind of time pressure on them.

That is not what happens according to the PHB and Sage Advice.

A party moving at a normal pace makes Perception/Investigation checks to detect the trap (I would roll in secret unless someone has mentioned specifically looking for it).

A party moving at a fast pace has a -5 penalty to their Perception/Investigation checks.

A player with Dungeon Delver has Advantage on checks to detect traps (and resistance to damage). The last benefit is odd because it doesn't say anywhere that you can't search for traps at a fast or normal pace in the rules. (http://www.sageadvice.eu/2016/04/25/dungeon-delver-feat-phatom-rule/)

The rules say nothing about being unable to search for threats or spot trouble while traveling fast, only that you suffer a passive penalty while doing so.

@OP: If the players do not mention searching for traps/threats, use their passive scores. If someone wants to look for them, have them roll for it.

If there's nothing there, and they don't spot anything -> Tell them they don't see anything.
If there's something there, and they don't spot anything -> Tell them they don't see anything.
If there's something there, and they spot something -> Tell them what they see.
If there's nothing there, and they spot something -> You have a bigger problem.

[Specter]

That is not what happens according to the PHB and Sage Advice.

A party moving at a normal pace makes Perception/Investigation checks to detect the trap (I would roll in secret unless someone has mentioned specifically looking for it).

A party moving at a fast pace has a -5 penalty to their Perception/Investigation checks.

A player with Dungeon Delver has Advantage on checks to detect traps (and resistance to damage). The last benefit is odd because it doesn't say anywhere that you can't search for traps at a fast or normal pace in the rules. (http://www.sageadvice.eu/2016/04/25/dungeon-delver-feat-phatom-rule/)

The rules say nothing about being unable to search for threats or spot trouble while traveling fast, only that you suffer a passive penalty while doing so.

@OP: If the players do not mention searching for traps/threats, use their passive scores. If someone wants to look for them, have them roll for it.

If there's nothing there, and they don't spot anything -> Tell them they don't see anything.
If there's something there, and they don't spot anything -> Tell them they don't see anything.
If there's something there, and they spot something -> Tell them what they see.
If there's nothing there, and they spot something -> You have a bigger problem.

Ok, so trade "slow" for "normal". Advantage applied to a passive check is +5, and we're good. I don't think it's fair to forbid checks because they're going fast--but the checks to be worse, of course.

[Coffee_Dragon]

@OP: If the players do not mention searching for traps/threats, use their passive scores. If someone wants to look for them, have them roll for it.

A party that's "travelling along" should use passive scores regardless. It's not the party searching "actively" or "passively" that determines whether you use active or passive checks.

[Occasional Sage]

I've been known to ask for checks for no reason, also, just to keep players paranoid. Doing that too often ruins the gambit, though, and even once has a tendency to slow the game down as everybody scurries around like ants from a kicked hill to figure out what they missed that might kill or enrich them.

[lunaticfringe]

I've been known to ask for checks for no reason, also, just to keep players paranoid. Doing that too often ruins the gambit, though, and even once has a tendency to slow the game down as everybody scurries around like ants from a kicked hill to figure out what they missed that might kill or enrich them.

Oh I'm totally gonna start doing this! Thanks!

[JAL_1138]

Traps are detected by either sending a hired redshirt ahead or prodding with a 10ft pole. </grognard>

[Occasional Sage]

Traps are detected by either sending a hired redshirt ahead or prodding with a 10ft pole. </grognard>

Summoned animals are good for that too.

[andylatham82]

Thanks for all the thoughts on the matter guys, you answered my question well. :)

[Ninja_Prawn]

If there's nothing there, and they spot something -> You have a bigger problem.

That's not a problem; it's an opportunity! Maybe they found a clue, or a bit of treasure, or a new species of insect... :smalltongue: