Can you use detect magic to detect magic from a magic trap? Could people also provide an explanation as to why or why not, please?
Well, it's a magical item so it'd say it would.
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-It takes no special skill to locate traps. All classes can use perception.
-Detect magic allows the caster to see a magical aura and identify a school with a skill check.
Combining these two things I'd say yes, but you don't detect the trap itself with detect magic, but it would raise questions why a magic aura is radiating in the middle of a hallway. If the perception to investigate is high enough they may find it, so it's like an early warning system.
When dealing with magic there are always exceptions. Illusions and invisibility are the big ones. I'm of the belief Detect magic doesn't trump invisibility so a trap incorporating this magic won't be spotted in this fashion.
Illusionary traps are tricky. They should have a magic aura but unless there is a successful will save for interacting the aura should appear as a different school.
These are my interpretations only, and your experiences may vary by GM.
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IMO detect magic doesn't let you see magic, it just magically informs you that it is present or absent and the vague location(5' square). So the caster would know there is an aura ahead, and might possibly ID it with the proper skill checks, but that doesn't inform how to disarm it or bypass it - you'd still need Disable Device for that.
Depending on the trigger (some use 'sight' via arcane eye or other divinations) and it's location it could be blocked by materials (especially lead sheets). It's reasonable to assume most trap builders would incorporate lead to block divinations where possible. It wouldn't render all traps undetectable, but some.
Something to keep in mind.
How i always ruled it:
- You need to analyze the target of detect magic, if you havent perceived it, you cannot "detect it's magic", you cannot see the auras, you cannot tell the magic's properties, etc.
I'm assuming you were aware that you can use Detect Magic to sense (but not ID) auras through solid objects that you couldn't possibly see normally when you made your house rule, right?
Which are normally paper, cloth and leather bags, so you can see if someone is wearing a magic amulet.
In my house rule, you are still seeing the "target", in this example, a person or monster carrying the magic item under his clothes.The text says that it can penetrate barriers, but what defines a barrier in the rules? Clothes are barriers? Can detect magic penetrate clothes?
What this prevents is someone automatically detecting virtually any magical trap ever designed if they are triggered by proximity or use the alarm trigger. Like @paulicus pointed out, we have to assume that all trap builders are using lead to block their traps, otherwise they can be ignored by a cantrip or certain very cheap magic items that grant detect magic at will, but a RaW reading of the magical traps doesn't say that.
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The text says that it can penetrate barriers, but what defines a barrier in the rules?
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.
The spell can detect magical auras in the next damn room.
Also:
3rd Round: The strength and location of each aura. the items or creatures bearing the auras are in line of sight, you can make Knowledge (arcana) skill checks to determine the school of magic involved in each.
The only thing that's contingent on line of sight is ID'ing the school. But you've already determined the strength and location, even without line of sight.
You can literally walk up to the outside of a brick house and, after three rounds, know how many magical auras are in the living room, where they are, and how strong they each are.
You can literally walk up to the outside of a brick house and, after three rounds, know how many magical auras are in the living room, where they are, and how strong they each are.
Which i am aware and completely not happy about. Thus why the house-rule, players never complained, and the spell still does the intended purpose without being superman's x-ray vision.
And i apply that to all detect X spells, you cant walk around a town using detect evil at will so you can burst into someone's house when they ping as a bad person.Back in 3.5 we had a FAQ explaining all those questions, but back then (2007 3.5's faq), detect magic wasnt at-will:
Is it possible for detect magic to locate an invisible
creature?
Yes, although not very efficiently. Remember that detect
magic reveals the location of magical auras over the course of 3
rounds. A creature rendered invisible by a spell or magical
effect could be located via detect magic, but only after 3 rounds
of concentration. Furthermore, the invisible creature must
remain within the spell’s area for the entire 3 rounds of
concentration; if the creature moves out of the area, the process
must start again from the beginning. However, even if
everything works according to plan, you still don’t necessarily
know that you’ve found an invisible creature—at best, the
caster of detect magic would know that she had located a faint
aura of illusion magic in a particular space.
Can you use detect magic to detect supernatural effects?
For example, can it detect a wildshaped druid?
Supernatural abilities are magical, and thus their effects
would produce magical auras. Although the detect magic spell
doesn’t have a line entry for supernatural effect, you can use
the same line as “Magic item (caster level)”—a supernatural
effect’s caster level is equal to the creature’s Hit Dice unless
noted otherwise (Monster Manual, page 315).
Can detect magic be used to identify magical traps?
Would nondetection block this?
Detect magic locates magical traps, but it can’t identify
anything more than the location and strength of the aura
revealed (and, with a successful Spellcraft check, the school of
magic involved). Thus, technically the spell doesn’t actually
reveal the fact that the magical trap is, in fact, a trap.
Nondetection wards a trapped object from detect magic
(requiring a caster level check to pierce the nondetection). An
even better option is Nystul’s magic aura, which can conceal a
magic trap’s aura (or change it to appear as that of another spell
of your choice).
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If you knew that was how it worked, why did you ask how the rules defined a barrier? Could've saved us both some time if you'd been a little clearer about what you acknowledged to be a houserule and what you thought was an interpretation of the published version. :/
Yeah, it was a rethorical question. I am not the OP.
I would expect anyone who goes to the expense of a serious magical trap (permanent, self resetting etc.) would make sure to cover it with a thin sheet of lead.
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I would expect anyone who goes to the expense of a serious magical trap (permanent, self resetting etc.) would make sure to cover it with a thin sheet of lead.
More likely, magic aura; a sheet of lead could potentially interfere with the trap itself.
In fact, in my own lair, I'd probably scatter trapless magic aura effects all over the place, with false auras of evocation and necromancy and all sorts of fun stuff. Then the actual traps would be magic aura'd into auralessness or, just to screw with intruders, weird crap like divination or conjuration (healing).
But I'm evil like that. >:D
I would expect anyone who goes to the expense of a serious magical trap (permanent, self resetting etc.) would make sure to cover it with a thin sheet of lead.
This is one possible "in game" answer to the situation, and makes a decent amount of sense. Thus, detect magic might find some traps (such as an alarm spell, etc.), but would not find more complicated traps.
Personally, I've just houseruled the detect magic spell to be Touch range. I find that it puts a bit of the mystery and danger back into basic exploration and interaction with the world. It also has the side effect of making illusions and traps more difficult to deal with, which sort of multiplies the additional mystery and danger. This may not be for every group of players, but I like it a lot.
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Personally, I've just houseruled the detect magic spell to be Touch range. I find that it puts a bit of the mystery and danger back into basic exploration and interaction with the world. It also has the side effect of making illusions and traps more difficult to deal with, which sort of multiplies the additional mystery and danger. This may not be for every group of players, but I like it a lot.
I like how 5E handled this and other similar "utility" spells: it's a 1st-level spell, but has the "ritual" tag, which lets a caster with the "Ritual Caster" class feature extend the casting time by 10 minutes in order to make it not cost a slot.
Spend a slot to find out now? Spend some time to save your resources? Decision! Depth! I like it! :D
Technically, yes. However I assume trap builders are aware and take steps to prevent it. Perhaps a custom and very minor version of mind blank specific to traps exists to prevent such divination. Were I a trap maker it's one of the first things I'd research.
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Also remember that "Magical areas, multiple types of magic, or strong local magical emanations may distort or conceal weaker auras." So if the magical trap is part of a big complex of magical traps, or if it's in the area of a powerful unhallow or guards and wards type effect, or if it happens to be guarding a cache of potions of different schools, it might not be easily detectable.
My take:
You probably cannot hide the magical parts of a trap behind lead (or anything else) - it's likely that the lead would break LOE for your trap. Either the trigger (perhaps an Alarm spell or a srying "eye") is blocked by the lead or it isn't, and if it isn't, then it's in LOE/LOS for detection spells and for plain old Perception checks.
Traps are fairly expensive. Magical traps are very expensive. Nobody would pay for a very expensive magical trap that any level 1 stooge could defeat at will with a CANTRIP.
Therefore I assume that the costs for such magical traps include features to hide the magic from detection spells. Consider it part of the package that the guy creating the trap includes a Magic Aura spell to prevent detection.
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The text says that it can penetrate barriers, but what defines a barrier in the rules?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.The spell can detect magical auras in the next damn room.
Actually, it will not, if we are speaking of medieval or renaissance walls and not of cardboard walls. Generally a medieval interior wall in a good house is larger than 1'. In a low quality house generally you have only a curtain or a wooden wall so detect magic will pass it.
Also:
3rd Round: The strength and location of each aura. the items or creatures bearing the auras are in line of sight, you can make Knowledge (arcana) skill checks to determine the school of magic involved in each.The only thing that's contingent on line of sight is ID'ing the school. But you've already determined the strength and location, even without line of sight.
You can literally walk up to the outside of a brick house and, after three rounds, know how many magical auras are in the living room, where they are, and how strong they each are.
i have seen a few house under construction in the US while I was visiting, so I have an idea of where you come from, but I have seen a great deal of farmer houses, city houses, manors, castles and so on built during the renaissance in Italy and none had exterior walls less than 1' tick. I doubt it is different in Golarion, especially seeing what go around there,
Obviously, Detect Magic can detect the auras of magical traps. Just as obviously, people concerned about competent intruders take steps to rectify that. Even more obviously, I got better things to do than providing detailed blueprints of a trap to inquisitive players.
Mostly, magical traps are re-hidden by assistants and apprentices using Magic Aura. If it's a tomb, someone spent the gold to make it permanent. If it's low-level stuff meant to keep the rabble out, or if it has fallen into disuse, it might be detectable.
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I would expect anyone who goes to the expense of a serious magical trap (permanent, self resetting etc.) would make sure to cover it with a thin sheet of lead.More likely, magic aura; a sheet of lead could potentially interfere with the trap itself.
In fact, in my own lair, I'd probably scatter trapless magic aura effects all over the place, with false auras of evocation and necromancy and all sorts of fun stuff. Then the actual traps would be magic aura'd into auralessness or, just to screw with intruders, weird crap like divination or conjuration (healing).
But I'm evil like that. >:D
Magically reinforced walls here and there, permanent light spells and/or everburning torches, casting prestidigitation to change the color of the walls, casting arcane mark (the best solution, it is permanent and you can set it to be invisible).
Remember:
Magical areas, multiple types of magic, or strong local magical emanations may distort or conceal weaker auras.
A arcane mark and a trap with a CL of 5 or less have a faint aura.
Start placing Arcane mark at random and one or more of them on the trap and either the characters will slow down to a crawl or they will not be able to sue detect magic to discover traps.I doubt that there are a lot of party that will go: "I detect magic on the area ahead." After 3 rounds: "There are magical auras, universal school there, there and there." "Good we will avoid them." After walking 60': "Stop, I will check again." Another 3 round waiting, then another 60' and so on.
It could be done, even avoiding the tedium at the table by the simple expedient of saying "We cast detect magic every time we enter a new area and wait to see what we find." But the party speed would become 60' every 4 round. Your minute/level spells will last very little.
BTW, there are easy solutions on the part of the trap builder against people doing that:
- put the trap behind a corner, far away that it is hidden by the wall thickness until you pass the corner but close enough that the people crossing the corner are hit by it.
- place the trap in a deep and narrow niche, possibly hiding the opening with a small layer of plaster. It the trap is far back enough you can't detect it trough the wall, but when you are in front of the opening, if it has the wight properties, it will detect you and trigger.
I think Grey Mage had the right idea.
It's very unlikely that someone competent enough to create a magical trap in the first place is going to somehow forget about the properties of a cantrip while making the trap.
So you're almost certainly going to need to make a perception check in the first place to even discover the trap exists, magical or not. Once that's done you can start focusing in with detect magic to determine more info. If a GM is letting you detect magical traps with a zero-level spell, then more power to you I guess. But it just seems like a very unlikely situation.
Or a potentially VERY devious situation. Obvious weaksauce magical trap that you find easily, followed closely by a more deadly, well-hidden trap right after when you feel like you're safe. ;)
So only one person in this thread (Jiggy) has noted that Magic Aura can create 'null auras', making Detect Magic useless?
Literally, it shuts down this Detect Magic tactic, unless you are immune to Illusion (Glamers), or use Identify instead.
(and succeed on Will check in the latter case)
Magic Aura has a 1 DAY/Level duration, as well, so certainly any trap with an active owner/interested party would be so maintained.
Really, this or similar topic seems to always come up, and almost everybody seems unaware of
the functionality of a 1st level spell, which anybody who doesn't want their magic traps trivially detected will use.
Please adjust your game world assumptions accordingly.
Likewise my PCs often use it to disguise their magical gear if they want to appear more unassuming,
lighting up like a christmas tree doesn't fit in with how a low level humanoid should look like,
so they Null Aura or LOWER CL Aura most gear, thus appearing more mundane/average to anybody Detecting/etc.
The Day/level duration means they can keep a large amount of object auras masked,
only 're-upping' one or a few each day... The trick can also be used to give the most mundane PC/ NPC follower
the highest level magical auras in the party, making them seem like the highest level/primary caster of the group (when they aren't).
Of course, anybody worth their snot doesn't place a huge amount of value in Detect Magic auras for this reason.
Again, it is a matter of what commonly available spells do, and how that plays out in the game world.
Just like if there is some uber-powerful option, that means NPCs will tend to take that option,
and/or be aware of it and take measures which defend against/counter that option.