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1 person marked this as FAQ candidate. |

I've always been under the assumption that just as characters without Trapfinding can find a non-magical trap, but might not be able to disable it, a character with Detect Magic can still Detect the magic stored in a Magical trap. Be it a glyph, rune, or some kind of spell trigger trap.
I just re-read the section on Traps from the core book, and didn't see anything about the magic traps not showing up under Detect Magic, but I've talked to two players/gms lately that think that magical traps are "hidden" somehow from detect magic.
Does anyone have a reference one way or the other? Otherwise I'll just go back to my thinking that - yes, with detect magic up, you can determine what is magical, determine its aura. if you roll well enough, maybe get the spell if there's some effect in place. but without Trapfinding class feature, characters have to bypass it somehow or just settle on triggering it.

Banecrow |

I've always run it as detect magic will show you there is magic there and you can find magic traps that way. But here is a good example to remember, say the wizard has detect magic up and sees a magical glyph 40 feet in front of him on a statue. The party stops and the rogue starts to go forward, but triggers the activation of the trap which is 10' infront of the party. The gliph activates and a 10d6 fireball flies to the spot where the trap was activated.
The party was too busy paying attention to the presence of the magical trap to notice the trigger component was a plate in the floor that when pressed down activated the glyph.
Traps have many parts and a magical trap very well could have non magical parts to it that can be used to activate the magical portion.

Tinalles |
+1 on what Jiggy said.
Also note, you can add magic aura to the trap's construction requirements to conceal its aura and adjust the price accordingly. But unless the trap's description explicitly notes this, assume that it will ping on detect magic.

Grick |

Elements of a Trap:
"Magic traps are further divided into spell traps and magic device traps. Magic device traps initiate spell effects when activated, just as wands, rods, rings, and other magic items do."
"Spell traps are simply spells that themselves function as traps. Creating a spell trap requires the services of a character who can cast the needed spell or spells, who is usually either the character creating the trap or an NPC spellcaster hired for that purpose."
The spell Fire Trap is a Spell trap. If someone pointed a detect magic spell at a object under the effects of fire trap, they would detect the presence of a magical aura. Round 2 they would detect the number of auras and the strength of the strongest. Round 3 they would learn the strength and location of each aura, as well as being able to attempt a Knowledge (arcana) skill check to determine the school of magic involved (in this case: abjuration).
A "Burning Hands Trap" is an example Magic device trap. It's created with the spells alarm and burning hands. While the rules don't explicitly say that you would detect the magical auras of those spells, it's pretty reasonable to assume that you would.

John Templeton |

I am a bit on the fence about this one as Detect Magic in this case does make the rogue a little less important (or a lot in some people's thoughts).
This is the way I handle it.
Magic Device Traps, No Detect Magic. It is a trap and the maker most likely will try and hide the magic bits in some matter via layers, lead or something else most likely.
Spell Traps, Yes Detect Magic. The very nature of these traps make them a bit more 'exposed'.
Just my two cents.

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i don't see it making a rogue more or less important. I just see it as giving a party options, and not forcing anyone to play something that they don't want to.
Detect magic doesn't point out the Trigger like Banecrow pointed out in his example.
and the DC to detect the magical trap without Detect Magic being involved is a base DC of 25. So the rogue, who would need Trap Spotter talent or be lucky enough to be searching, would need a pretty high perception to spot it on average. Not something a low level party should be subjected to very frequently. A typical 1st level rogue with Trapfinding and a 12 wis would have a +6 to find traps. they'd have a 10% chance of detecing a Ray of Frost trap. So I'd hope the adventure didn't have magical traps for low level parties.
A party without a rogue ( common enough in PFS ) , often relies on someone acting as the searcher with a high Perception check. But there's no chance of them spotting magical traps. Without Detect Magic working to at least detect that there's something dangerous ahead, it can be pretty bad for a party without a rogue ( or with a rogue who has traded away his Trapfinding class feature )
Without a Rogue or a caster with Detect Magic, I hope the party is high enough level to be able to take a hit from a rough magical trap now and then and survive.

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and the DC to detect the magical trap without Detect Magic being involved is a base DC of 25. So the rogue, who would need Trap Spotter talent or be lucky enough to be searching, would need a pretty high perception to spot it on average. Not something a low level party should be subjected to very frequently. A typical 1st level rogue with Trapfinding and a 12 wis would have a +6 to find traps. they'd have a 10% chance of detecing a Ray of Frost trap. So I'd hope the adventure didn't have magical traps for low level parties.
Or at least, magical traps should be in places that make sense (like a creepy door or altar) where she can choose to search and Take 20. (This is even one of the Core Rulebook's suggested uses of the Take 20 mechanic.)
A party without a rogue ( common enough in PFS ) , often relies on someone acting as the searcher with a high Perception check. But there's no chance of them spotting magical traps.
Wrong. ANYONE can detect a magical trap with Perception. It takes a rogue (or someone with a similar ability) to DISABLE it.

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Wrong. ANYONE can detect a magical trap with Perception. It takes a rogue (or someone with a similar ability) to DISABLE it.
A good reminder to re-read abilities every now and then. Thanks Jiggy.
Trapfinding: A rogue adds 1/2 her level to Perception skill checks made to locate traps and to Disable Device skill checks (minimum +1). A rogue can use Disable Device to disarm magic traps.
Magic traps may be disarmed by a character with the trapfinding class feature with a successful Disable Device skill check (DC 25 + spell level). Other characters have no chance to disarm a magic trap with a Disable Device check.
Ok, so anyone can find them. Though what they find may be even more perplexing to them. ( "you notice a faint blue glow on a tile of the floor" ) They still have to avoid, or try and just trigger the trap.
When I GM, most attempts to "trigger it safely" I construe as Disable Device attempts, and when possible have them trigger on the attempting PC as a failed DD attempt. Unless they have ranks of course.

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aye. Rogues were just the only ones with it when the Environment section of the CRB was written. It was written referring to the Trapfinding class feature at least, while the skill and the Rogue class just refer to themselves. There's the Ranger - Trapper archetype, off the top of my head. I'm not sure which prestige classes grant Trapfinding.

Christopher Rowe Contributor |

aye. Rogues were just the only ones with it when the Environment section of the CRB was written. It was written referring to the Trapfinding class feature at least, while the skill and the Rogue class just refer to themselves. There's the Ranger - Trapper archetype, off the top of my head. I'm not sure which prestige classes grant Trapfinding.
Hmmm. My mac tells me that the word "trapfinding" appears in 31 of the .pdfs in my Pathfinder folders. I suppose I could go through 'em and see what I can see. Not before supper though!

spalding |

Jiggy is correct about constructed magic traps. But most magic spell traps still require Trapfinding to find. I personally think this is a holdover from 3.5 but its currently written that way.
- Gauss
No most magic spell traps do not require trapfinding to find.
A rogue adds 1/2 her level to Perception skill checks made to locate traps and to Disable Device skill checks (minimum +1). A rogue can use Disable Device to disarm magic traps.
Note nothing in the ability gives the rogue a special means of finding magical traps -- merely the ability to disable them.
Also from the trap rules:
Magic: Many spells can be used to create dangerous traps. Unless the spell or item description states otherwise, assume the following to be true.
A successful Perception check (DC 25 + spell level) detects a magic trap before it goes off.
Magic traps permit a saving throw in order to avoid the effect (DC 10 + spell level × 1.5).
Magic traps may be disarmed by a character with the trapfinding class feature with a successful Disable Device skill check (DC 25 + spell level). Other characters have no chance to disarm a magic trap with a Disable Device check.
Please note again that anyone can detect a magic trap with a perception check.
Now some specific trap like spells might have specific language, but those are specific trap like spells not traps in and of themselves.

spalding |

Just to be a completist, there are other ways to gain Trapfinding, through prestige classes and so on.
Annoyingly, I can't remember any of them right now and I have to go stir the potatoes.
Pathfinder Delver maybe?
seeker sorcerer, urban and trapper ranger are some off the top of my head.
cryptbreaker alchemist, archaeologist detective and sandman bard also offer either trapfinding or variants on trapfinding.
I haven't gone through the prestige classes yet, and I think I might have missed a few other abilities but there is a start.

John Templeton |

John Templeton wrote:I am a bit on the fence about this one as Detect Magic in this case does make the rogue a little less importantSo I guess you plan to modify the Perception skill as well?
No, why?

Gauss |

Abraham:
I stated that most spell traps require Trapfinding to find them. I stand by that statement.
Here is a list of spell traps in the CRB that require Trapfinding:
Fire Trap, Glyph of Warding, Snare, Spike Growth, Spike Stones, and Symbol spells.
Every single one of them states that Trapfinding is required.
If your point is that they are not called spell traps then we have this:
Spell traps are simply spells that themselves function as traps. Creating a spell trap requires the services of a character who can cast the needed spell or spells, who is usually either the character creating the trap or an NPC spellcaster hired for that purpose.
If your point is regarding my usage of the word 'most' then I ask this: Please find more than the number of spell traps that I quoted (6 if you count all the symbol spells as one spell and both Glyph spells as one spell) that require a perception check to detect but do NOT require Trapfinding.
- Gauss
Edit: Removed Explosive Runes and Teleportation Circle. I put them in erroneously as those are two spells that do not state they require Trapfinding to detect them.

Quatar |

If someone thinks a cantrip is too easy for detecting magical traps, remind them that the Perception skill can do it too, even without Trapfinding.
While that is true it's not that easy.
Any wizard, sorcerer, cleric or anyone can just say "I cast Detect Magic and leave it on while we're in here, recast it when it runs out" and ping, automatically detects all magic traps, 6 seconds after entering a room (thats when he gets the "Oh something is here" feeling).Someone who wants the chance to detect that same stuff with Perception, not only does he have to constantly roll Perception, he has to invest skills into it, and he actually has to roll high enough.
So no, I'm sorry "Detect Magic should work, because Perception does too" just doesn't cut it.
I'm sorry, I'm with John Templeton on this, if someone builds a magic trap he'll layer it with lead or will hide it somehow else so the magic can't be detected before it goes boom.

Gauss |

Requirements to use Detect Magic as a trap detector:
1) Standard action every round.
2) The person using it must be in front of the party.
3) The area being explored must not have any other magic.
#1 may slow the group down.
#2 means that if there is someone else with magic on them in front the detector must wait three rounds in order to determine the location of magic sources. Imagine doing that every 3 rounds. We move, detect, detect, detect. Repeat.
#3 is basically the same as #2 but may also mask the aura of the trap.
- Gauss

therealthom |

Abraham:
I stated that most spell traps require Trapfinding to find them. I stand by that statement.
Here is a list of spell traps in the CRB that require Trapfinding:
Explosive Runes, Fire Trap, Glyph of Warding, Snare, Spike Growth, Spike Stones, Symbol spells, and Teleportation CircleEvery single one of them states that Trapfinding is required.
If your point is that they are not called spell traps then we have this:
CRB p417 wrote:Spell traps are simply spells that themselves function as traps. Creating a spell trap requires the services of a character who can cast the needed spell or spells, who is usually either the character creating the trap or an NPC spellcaster hired for that purpose.If your point is regarding my usage of the word 'most' then I ask this: Please find more than the number of spell traps that I quoted (8 if you count all symbol spells as one spell) that require a perception check to detect but do NOT require Trapfinding.
- Gauss
At least three of them do not state that Trapfinding is the sole necessary and sufficient requirement to find a magical trap.
... Magic traps such as explosive runes are hard to detect and disable. A character with the trapfinding class feature (only) can use Disable Device to thwart explosive runes. The DC to find magic traps using Perception and to disable them is 25 + spell level, or 28 for explosive runes.
I would read this as Trapfinding and Disable Device are needed to deactivate a trap, but not to detect it. I would allow detect magic.
Magic traps such as fire trap are hard to detect and disable. A character with trapfinding can use the Perception skill to find a fire trap and Disable Device to thwart it. The DC in each case is 25 + spell level (DC 27 for a druid's fire trap or DC 29 for the arcane version).
Note: Magic traps such as glyph of warding are hard to detect and disable. A rogue (only) can use the Perception skill to find the glyph and Disable Device to thwart it. The DC in each case is 25 + spell level, or 28 for glyph of warding.
Neither prohibit detect magic from finding the trap.
I will agree anyone who doesn't cover a magic trap with a (non)magic aura whenever is not serious about his traps. I think it would almost be a given.

Whale_Cancer |

I also think anyone who doesn't cover a magic trap with a (non)magic aura whenever he can is an idiot. That would stop detect magic cold.
You alter an item's aura so that it registers to detect spells (and spells with similar capabilities) as though it were nonmagical, or a magic item of a kind you specify, or the subject of a spell you specify. If the object bearing magic aura has identify cast on it or is similarly examined, the examiner recognizes that the aura is false and detects the object's actual qualities if he succeeds on a Will save. Otherwise, he believes the aura and no amount of testing reveals what the true magic is.
Considering it is a 1st level spell, the Will save tends to not be very high. It's really not that effective from my experience in trying to deploy it as a DM.

cwslyclgh |

I'm sorry, I'm with John Templeton on this, if someone builds a magic trap he'll layer it with lead or will hide it somehow else so the magic can't be detected before it goes boom.
While undoubtably true of some traps and trap makers, not all of them are going to do so, to say that ALL magic traps are thus undetecable with detect magic would be following the same path as the DM who never uses the charge action against characters that have a brace weapon, or only uses oozes, incorporeal undead and elementals as monsters so the sneak attacks and critical hits are useless.

therealthom |

therealthom wrote:I also think anyone who doesn't cover a magic trap with a (non)magic aura whenever he can is an idiot. That would stop detect magic cold.Quote:You alter an item's aura so that it registers to detect spells (and spells with similar capabilities) as though it were nonmagical, or a magic item of a kind you specify, or the subject of a spell you specify. If the object bearing magic aura has identify cast on it or is similarly examined, the examiner recognizes that the aura is false and detects the object's actual qualities if he succeeds on a Will save. Otherwise, he believes the aura and no amount of testing reveals what the true magic is.Considering it is a 1st level spell, the Will save tends to not be very high. It's really not that effective from my experience in trying to deploy it as a DM.
...Saving Throw none; see text; Spell Resistance no
You alter an item's aura so that it registers to detect spells (and spells with similar capabilities) as though it were nonmagical, or a magic item of a kind you specify, or the subject of a spell you specify. If the object bearing magic aura has identify cast on it or is similarly examined, the examiner recognizes that the aura is false and detects the object's actual qualities if he succeeds on a Will save. Otherwise, he believes the aura and no amount of testing reveals what the true magic is.
...
Detect magic doesn't net you a save. Only identify does.
How many PC casters prep identify multiple times per day?

Gauss |

My bad therealthorn, I got a bit search happy. LOL I knew better. I have removed Explosive Runes and Teleportation Circle. The rest still require Trapfinding for the perception check. Including Fire Trap and Glyph of Warding.
Fixed.
BTW, what is your source for Glyph of Warding? The 5th printing of the CRB does not use the phrase 'rogue (only)'.
- Gauss

Whale_Cancer |

@therealthom: I guess the issue is the "or is similarly examined" line; identify is just detect magic with a +10 bonus to identify an item's properties (with traps being items). Seems like "similarly examined" to me.
Also, the general rule for illusions still apply:
Saving Throws and Illusions (Disbelief): Creatures encountering an illusion usually do not receive saving throws to recognize it as illusory until they study it carefully or interact with it in some fashion.
A successful saving throw against an illusion reveals it to be false, but a figment or phantasm remains as a translucent outline.
A failed saving throw indicates that a character fails to notice something is amiss. A character faced with proof that an illusion isn't real needs no saving throw. If any viewer successfully disbelieves an illusion and communicates this fact to others, each such viewer gains a saving throw with a +4 bonus.
I would interpret using detect magic to be sufficient interaction to attempt disbelief.
Also, there is the issue that Magical Aura is itself a spell. How does that interact with detect magic? Can you detect that magical aura spell? I suppose if integrated as part of a trap and not just cast on a trap, this wouldn't be an issue. However, with a level/day casting time it is probably more cost efficient for any maintained dungeon or site to have the spell recast rather than integrated into the trap (increasing cost).

therealthom |

My bad therealthorn, I got a bit search happy. LOL I knew better. I have removed Explosive Runes and Teleportation Circle. The rest still require Trapfinding for the perception check. Including Fire Trap and Glyph of Warding.
Fixed.
- Gauss
It's cool. In a gentlemanly and friendly way, I will persist in my reading of those spells that detect magic is not prohibited from finding Fire Trap and Glyph while agreeing that you must have Trapfinding to use Perception to find them. In no way do I condemn your reading and wish the best at your table.

Gauss |

Oh, I do allow detect magic to detect them. I support that position. :) My position regarding Trapfinding is that not all magic traps (namely, a significant portion of the subset of Magic Traps that are Spell Traps) can be detected by everyone using Perception. That does not preclude detect magic from being used.
An interesting note: Teleportation Circle has an incomplete sentance. It was using the same sentance structure as the other 'trapfinding can use the Perception skill' spells but then it cut out everything between 'the' and 'Disable'.
- Gauss

therealthom |

@therealthom: I guess the issue is the "or is similarly examined" line; identify is just detect magic with a +10 bonus to identify an item's properties (with traps being items). Seems like "similarly examined" to me.
Also, the general rule for illusions still apply:
Quote:Saving Throws and Illusions (Disbelief): Creatures encountering an illusion usually do not receive saving throws to recognize it as illusory until they study it carefully or interact with it in some fashion.
A successful saving throw against an illusion reveals it to be false, but a figment or phantasm remains as a translucent outline.
A failed saving throw indicates that a character fails to notice something is amiss. A character faced with proof that an illusion isn't real needs no saving throw. If any viewer successfully disbelieves an illusion and communicates this fact to others, each such viewer gains a saving throw with a +4 bonus.
I would interpret using detect magic to be sufficient interaction to attempt disbelief.
Also, there is the issue that Magical Aura is itself a spell. How does that interact with detect magic? Can you detect that magical aura spell? I suppose if integrated as part of a trap and not just cast on a trap, this wouldn't be an issue. However, with a level/day casting time it is probably more cost efficient for any maintained dungeon or site to have the spell recast rather than integrated into the trap (increasing cost).
I hadn't considered the "or is similarly examined" line. I was assuming that mention of identify implied its less powerful cousin detect magic would be insufficient to net a save, while leaving the door open for supernatural abilities and such.
I interpret the non-magical option of Magic Aura to mean that aura itself is not detectable. It seems rather pointless to mask something as non-magical while leaving a nice illusion aura over it. It would almost force a caster to disguise the type of spell used in the trap instead of just hiding the aura.
Good points though.

therealthom |

Oh, I do allow detect magic to detect them. I support that position. :) My position regarding Trapfinding is that not all magic traps (namely, a significant portion of the subset of Magic Traps that are Spell Traps) can be detected by everyone using Perception. That does not preclude detect magic from being used.
An interesting note: Teleportation Circle has an incomplete sentance. It was using the same sentance structure as the other 'trapfinding can use the Perception skill' spells but then it cut out everything between 'the' and 'Disable'.
- Gauss
Then we're ageement, and I misinterpreted your post I first quoted. My apologies.
I'd never noticed the teleportation circle glitch. I seldom play those rarified levels.

RainyDayNinja RPG Superstar Season 9 Top 32, RPG Superstar 2014 Top 16, RPG Superstar 2013 Top 16 |

Jiggy wrote:If someone thinks a cantrip is too easy for detecting magical traps, remind them that the Perception skill can do it too, even without Trapfinding.While that is true it's not that easy.
Any wizard, sorcerer, cleric or anyone can just say "I cast Detect Magic and leave it on while we're in here, recast it when it runs out" and ping, automatically detects all magic traps, 6 seconds after entering a room (thats when he gets the "Oh something is here" feeling).Someone who wants the chance to detect that same stuff with Perception, not only does he have to constantly roll Perception, he has to invest skills into it, and he actually has to roll high enough.
So no, I'm sorry "Detect Magic should work, because Perception does too" just doesn't cut it.
I'm sorry, I'm with John Templeton on this, if someone builds a magic trap he'll layer it with lead or will hide it somehow else so the magic can't be detected before it goes boom.
A character invested in Perception can do the same thing, just saying "I take 10 on Perception every round while we're in here," and pinging on any traps he can meet the DC of.

Quatar |

Quatar wrote:While undoubtably true of some traps and trap makers, not all of them are going to do so, to say that ALL magic traps are thus undetecable with detect magic would be following the same path as the DM who never uses the charge action against characters that have a brace weapon, or only uses oozes, incorporeal undead and elementals as monsters so the sneak attacks and critical hits are useless.
I'm sorry, I'm with John Templeton on this, if someone builds a magic trap he'll layer it with lead or will hide it somehow else so the magic can't be detected before it goes boom.
That would certainly be true if the only purpose of Detect Magic was to detect magic traps. But then it would be called Detect Magic Traps.
And I don't think you seriously want to suggest that Detect Magic has no other purpose than traps? There's a reason that pretty much everyone who can prepare it prepares it every day. And that reason is rarely traps.
Sneak attack on the other hand has only the purpose to do damage.

Whale_Cancer |

My point is that completely eliminating a viable tactic because you don't happen like it is piss-poor GMing.
If a trapsmith has the option of using magical aura to prevent his trap from being detected by a cantrip, then it is piss-poor trap design to not use magical aura. This is a verisimilitude issue.
Also, if you agree with my interpretation of magical aura, detect magic will still be able to foil the deception with a will save. This in no way eliminates detect magic as a viable option.

cwslyclgh |

I was actually talking to to Quatar, not to you WC. he stated earlier that all magical traps should be lead lined or some such to foil detect magic.
Not all trap creators will necessarily have access to magic aura, but I agree with you that a a fair number of them should be modified that way, just as I think some could be hidden in lead lined areas to block detection.
My problem is with those that simply say categorically that 'detect magic can never find a magic trap just because I don't want it to'.

Whale_Cancer |

I was actually talking to to Quatar, not to you WC. he stated earlier that all magical traps should be lead lined or some such to foil detect magic.
Not all trap creators will necessarily have access to magic aura, but I agree with you that a a fair number of them should be modified that way, just as I think some could be hidden in lead lined areas to block detection.
My problem is with those that simply say categorically that 'detect magic can never find a magic trap just because I don't want it to'.
My apologies, sir. I obviously missed that.

John Templeton |

I was actually talking to to Quatar, not to you WC. he stated earlier that all magical traps should be lead lined or some such to foil detect magic.
Not all trap creators will necessarily have access to magic aura, but I agree with you that a a fair number of them should be modified that way, just as I think some could be hidden in lead lined areas to block detection.
My problem is with those that simply say categorically that 'detect magic can never find a magic trap just because I don't want it to'.
Well WC was agreeing with me though my exact statement was that Detect Magic would see Spell Traps but not Magic Device Traps.
Though I find it poor taste for you to insult my entire GM style over my interpation of a clear grey area.

asthyril |

I do not see the need for a FAQ. I do not see why detect magic would not find magical traps. All magic creates an aura (unless it says otherwise) and no traps claim to not have an aura. therefore detect magic will detect them.
THAT BEING SAID There is one thing i would like to point out, that i do not believe has been mentioned in this post, to the DMs-that-hate-players-finding-my-magic-traps-so-easily crowd.
blah blah a bunch of stuff
The spell can penetrate barriers, but 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or dirt blocks it.
anyone who is going to shell out the gold for a magical trap, can surely shell out a little more for a thin layer of lead to surround it.
VIOLA!! magical trap that thwarts detect magic.

Troubleshooter |

I'm very interested in the idea that a trap's trigger might not detect as magical.
When my group was first hashing over how the rules worked, we determined that all of a trap could be figured out with Perception; you wouldn't accidentally step on a pressure plate because it wasn't "THE trap". So I suppose I just mentally transferred the magical glow to the trigger too.
Still, this has some interesting possibilities; for example, a trigger could be 60+ feet away from the trap's origin. A character cruising through with Detect Magic could trigger the trap -- and, in fact, suddenly sense magic when a bolt of fire beelines toward him from its origin 65 feet away -- because he stepped on a nonmagical pressure plate.
It also occurs to me that I've been allowing my Detect Magic-users to simultaneously search for traps with the party, but if Detect Magic is a Standard action, and searching with Perception (not just noticing creatures reflexively) is a Move action, then they should be moving no more than five feet a round with all that concentration.
I bet all that time tip-toeing around can translate into additional time for dungeon denizens to spy on them and prepare ambushes to make up for all the failed traps.

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A party without a rogue ( common enough in PFS ) , often relies on someone acting as the searcher with a high Perception check. But there's no chance of them spotting magical traps. Without Detect Magic working to at least detect that there's something dangerous ahead, it can be pretty bad for a party without a rogue ( or with a rogue who has traded away his Trapfinding class feature )
A caster with a high perception can cover both bases. Not difficult in PFS where several faction traits grant perception as a class skill.

cwslyclgh |

anyone who is going to shell out the gold for a magical trap, can surely shell out a little more for a thin layer of lead to surround it.
VIOLA!! magical trap that thwarts detect magic.
this has been mentioned up thread, and while it is a viable option sometimes, it would not always be employable ( it is hard to read a symbol of insanity that's in a lead box, for instance, and solid lead, no matter how thin of a layer blocks line of effect for spell effects).

cwslyclgh |

I'm very interested in the idea that a trap's trigger might not detect as magical.
That is an interesting idea, a mechanical trigger such as a pressure plate that triggers a magical trap rather than the usual magical proximity trigger (using an alarm spell). I may have to use one of those in the future.