Knowledge (Arcana)


Rules Questions


So I recently learned that know arcana can be used to "Identify a spell effect that is in place". Does this mean as a free or non action I can look at someone at make a knowledge check for each spell on them to see if I realize it's on them?

Like enemy has shield and mage armor up and I walk into fighting them. Do I look and make 2 know checks 1 each to see if I recognize it?
Do I look and make 1 check and get all effects that I reach?

I'm just trying to figure out how this works, cause this seems so cool.


You'd need to make separate checks for each effect you wish to identify. It should be a free action to do so.


You might need to make a Perception (or Spellcraft maybe?) check to notice the spells are there at all. Then Knowledge to determine which spells.


MrCharisma wrote:
You might need to make a Perception (or Spellcraft maybe?) check to notice the spells are there at all. Then Knowledge to determine which spells.

Like are you saying I need to be able to see the person the spells are on? Or are you saying that I'd need to beat some made up DC to notice the invisible barrier around them before I could know(arcana) to tell that it was mage armor?


RAW it isn't totally clear on the action it'd take, but a DM could certainly rule it's a free action.

But I'd probably rule that Detect Magic or some such has to be up, similar to using spellcraft to ID an item. I mean that takes 3 rounds and thorough examination. Seems bizarre that any layman with an arcana rank has at least a 10% chance of recognizing magical effects. And in that case it makes me think the wizard would be better at spotting magical traps than a rogue. Besides, the situation of being in the middle of a fight isn't conducive to decoding an active spell. Best option may be a house rule for something like IDing as a standard action if you're decently close? Though maybe that's too generous, if there's a Dispel Magic spammer PC. Makes that DC tons easier to hit.


Know arcana has these in the table

"Identify auras while using detect magic"
"Identify a spell effect that is in place"

I really doubt that you need detect magic up to identify a spell effect in place because it specifically says using detect magic on the one that needs detect magic.


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It's a free action. That is raw. The questionable part is whether or not you have to be able to "see" the spell effect. You can't literally "see" charm person. You can see stinking cloud.

I will start an FAQ on this later if nobody beats me to it.

edit: I mean it should be observable with your senses to include hearing and smelling. Being visible is not the only option, but I will still FAQ it because I am not 100% sure.


Chess Pwn wrote:
MrCharisma wrote:
You might need to make a Perception (or Spellcraft maybe?) check to notice the spells are there at all. Then Knowledge to determine which spells.
Like are you saying I need to be able to see the person the spells are on? Or are you saying that I'd need to beat some made up DC to notice the invisible barrier around them before I could know(arcana) to tell that it was mage armor?

DETECT MAGIC (+GREATER DETECT MAGIC)

Yep some arbitrary made up DC.

It takes 3 rounds of concentration with Detect Magic to discern the "The strength and location of each aura" within the target area. And by "strength" see they mean pretty close:

Functioning spell (spell level):
3rd or lower = faint aura
4th - 6th = moderate aura
7th - 9th = strong aura
10th+ = overwhelming aura (deity level spells)

This is all done with only a cantrip, so I don't think it'd be game breaking to allow someone to do something similar with a skill-check. But it does seem unlikely that they intended for it to be easier to do without using this spell than it is with the spell.

Now if you use Detect Magic to identify that someone has spells on them then you don't need a separate perception check or anything. You can then use your Knowledge:Arcana to identify which spells are in effect (probably with a bonus since you now have an idea what their power level is).

This is all purely speculative from my part by the way, I'm not a great rules-lawyer. But I hope my logical leaps are all pretty clear and easy to follow. Also I'm not against someone arguing with me here. Keep an open mind and all that.


but you don't need detect magic for know arcana, if you needed it it would say in either detect magic that you can make know arcana checks to see active spell effects, or in know arcana it would say you needed detect magic for it.
So detect magic isn't needed for determining active spells effects.

Scarab Sages

Chess Pwn wrote:

So I recently learned that know arcana can be used to "Identify a spell effect that is in place". Does this mean as a free or non action I can look at someone at make a knowledge check for each spell on them to see if I realize it's on them?

Like enemy has shield and mage armor up and I walk into fighting them. Do I look and make 2 know checks 1 each to see if I recognize it?
Do I look and make 1 check and get all effects that I reach?

I'm just trying to figure out how this works, cause this seems so cool.

You'd have to Observe the spell enough to attempt a knowledge check to remember about that spell. It would have to be physical enough, where you could observe the spell to some degree.

So if you walk into an invisible wall, you could use knowledge arcana to recall that invisible walls are a thing, and that they could be accomplished by the such and such spell (the one whose DC you rolled against).

Appraise is used to notice magic effects on Items, and Enchantments on Creatures. Knowledge arcana could then be applied as a free action (to recall what you already know about such spells based on how the object or creature is influenced by them).

Grand Lodge

Murdock Mudeater wrote:


Appraise is used to notice magic effects on Items, and Enchantments on Creatures. Knowledge arcana could then be applied as a free action (to recall what you already know about such spells based on how the object or creature is influenced by them).

Afraid appraise does not do those things unless you're using the Unchained Rogue's skill unlock with it. And even then it only does the item part.

Did you mean Spellcraft per chance?

Scarab Sages

Jurassic Pratt wrote:
Murdock Mudeater wrote:


Appraise is used to notice magic effects on Items, and Enchantments on Creatures. Knowledge arcana could then be applied as a free action (to recall what you already know about such spells based on how the object or creature is influenced by them).

Afraid appraise does not do those things unless you're using the Unchained Rogue's skill unlock with it.

Did you mean Spellcraft per chance?

Appraise is correct to ID that an item has magic properties. You could then use Knowledge Arcana to ID an active spell effect, if it was applied to that weapon, as per Knowledge Arcana. This would not ID magic items, just active spells currently affecting items (so you could determine it a Sword affected by Magic Weapon, but not that it was a +1 sword).

As for Enchantments on creatures, yeah, I'm mixed up there. It's Sense Motive that detects Enchantments on creatures. Doesn't ID the enchantment, but would be enough to do a knowledge check to observe an active spell on the target.

And this is CRB uses of skills. The presence of Pathfinder Unchained doesn't prevent players from using the CRB as written (until they FAQ it, I suppose).


Have you ever played a video game where you run into characters that have tons of effects going? They'll have force fields, augmented speed, some sort of displacement effect and so on and so forth. The first time you see all of it at once, you have no idea what you're looking at. After you've played for a while, you know what all of it means the second it comes into view. It's a bit like that situation.

Grand Lodge

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Murdock, I think I misunderstood you. You're saying that you can use appraise to simply tell that an item has magical properties, right?

I mistakenly read that as you saying you could identify the magical properties with appraise.

My bad man.

Liberty's Edge

MrCharisma wrote:
Chess Pwn wrote:
MrCharisma wrote:
You might need to make a Perception (or Spellcraft maybe?) check to notice the spells are there at all. Then Knowledge to determine which spells.
Like are you saying I need to be able to see the person the spells are on? Or are you saying that I'd need to beat some made up DC to notice the invisible barrier around them before I could know(arcana) to tell that it was mage armor?

DETECT MAGIC (+GREATER DETECT MAGIC)

Yep some arbitrary made up DC.

It takes 3 rounds of concentration with Detect Magic to discern the "The strength and location of each aura" within the target area. And by "strength" see they mean pretty close:

Functioning spell (spell level):
3rd or lower = faint aura
4th - 6th = moderate aura
7th - 9th = strong aura
10th+ = overwhelming aura (deity level spells)

This is all done with only a cantrip, so I don't think it'd be game breaking to allow someone to do something similar with a skill-check. But it does seem unlikely that they intended for it to be easier to do without using this spell than it is with the spell.

Now if you use Detect Magic to identify that someone has spells on them then you don't need a separate perception check or anything. You can then use your Knowledge:Arcana to identify which spells are in effect (probably with a bonus since you now have an idea what their power level is).

This is all purely speculative from my part by the way, I'm not a great rules-lawyer. But I hope my logical leaps are all pretty clear and easy to follow. Also I'm not against someone arguing with me here. Keep an open mind and all that.

There is a bit more that you haven't cited:

Detect magic wrote:


3rd Round: The strength and location of each aura. If 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. (Make one check per aura: DC 15 + spell level, or 15 + 1/2 caster level for a nonspell effect.) If the aura emanates from a magic item, you can attempt to identify its properties (see Spellcraft).

So we have a generic rule:

"Identify auras while using detect magic Arcana 15 + spell level
Identify a spell effect that is in place Arcana 20 + spell level"
and a specific rule that you can identify the auras after 3 rounds of using detect magic.

As I read it, you can make the second skill check to identify the spell effect only after you have made the first "identifying the aura".
The action is free, but it require the prior knowledge you get from identifying the aura.
Some spell leave telltale effects (like a wall of fire), so they can be common knowledge and can be identified without the need to use detect magic, but for invisible effects without perceptible sign you need to use detect magic.

There are specific rules for specific spells, like Dominate person,

Quote:
Sense Enchantment: You can tell that someone's behavior is being influenced by an enchantment effect even if that person isn't aware of it. The usual DC is 25, but if the target is dominated (see dominate person), the DC is only 15 because of the limited range of the target's activities.

but those are specific rules and don't identify the spell, only the effect.

Scarab Sages

^That's part of Detect Magic.^

My point, is that without magic detection, but with observational deduction, you may be able to ID a spell with Arcana. It would have to be a spell that had physical symptoms enough where you could determine it, and it would have to be persistent enough where you could take the time to really look at it. And you'd have to notice it - not just see it, but actually notice that it was out of the ordinary.

For example, you encounter an illusion (figment). After successfully disbelieving it, you'd still be left with a translucent image of the original illusion. Depending on the capablities of the spell, you could probably determine if it was a Silent Image or some other spell. Yeah, some room for error, sure, enough to make an educated guess based on your knowledge of this sort of magic.

But this would only work if the spell lasted long enough to actually investigate it. Otherwise, it's just an illusion, not something that needs identifying.

You could also use arcana to determine the likely spells that could produce a certain effect that had already happened. For example, encountering a bunch of stone statues which looked too perfect to be art, you may attempt arcana to determine which magic spells are capable of this feat. Might turn out not to be a magic spell at all (like a bassilisk), but you could certainly use arcana to ID the spell it could have been if spells were involved.

Liberty's Edge

Murdock Mudeater wrote:

^That's part of Detect Magic.^

My point, is that without magic detection, but with observational deduction, you may be able to ID a spell with Arcana. It would have to be a spell that had physical symptoms enough where you could determine it, and it would have to be persistent enough where you could take the time to really look at it. And you'd have to notice it - not just see it, but actually notice that it was out of the ordinary.

For example, you encounter an illusion (figment). After successfully disbelieving it, you'd still be left with a translucent image of the original illusion. Depending on the capablities of the spell, you could probably determine if it was a Silent Image or some other spell. Yeah, some room for error, sure, enough to make an educated guess based on your knowledge of this sort of magic.

But this would only work if the spell lasted long enough to actually investigate it. Otherwise, it's just an illusion, not something that needs identifying.

You could also use arcana to determine the likely spells that could produce a certain effect that had already happened. For example, encountering a bunch of stone statues which looked too perfect to be art, you may attempt arcana to determine which magic spells are capable of this feat. Might turn out not to be a magic spell at all (like a bassilisk), but you could certainly use arcana to ID the spell it could have been if spells were involved.

Ok with that, but the original question was about identification as a free action when meeting someone with active spells.

Let's say I have used a fireball on some guy. I notice he suffer very little damage, so he has some kind of fire resistance.
I can have as much Knowledge arcana as I want, but I can't say if it is because he has a ring of energy resistance, fire, he has an active spell or he has some kind of natural fire resistance. Other factors can change that, like "I know he is an inquisitor and he has a flickering aura, so I can identify that as a resistance judgment with the right skill", but it isn't a simple Knowledge arcana check.

Scarab Sages

Diego Rossi wrote:

Ok with that, but the original question was about identification as a free action when meeting someone with active spells.

Let's say I have used a fireball on some guy. I notice he suffer very little damage, so he has some kind of fire resistance.
I can have as much Knowledge arcana as I want, but I can't say if it is because he has a ring of energy resistance, fire, he has an active spell or he has some kind of natural fire resistance. Other factors can change that, like "I know he is an inquisitor and he has a flickering aura, so I can identify...

Fireball isn't an active spell effect, it's instantaneous, so the skill would be spellcraft.

If you later, came across the room with the black marks where fireball had been cast, you could attempt Arcana to ID the spell based on the damage it caused. Or rather, to ID the magic that could have done this.

Liberty's Edge

Murdock Mudeater wrote:
Diego Rossi wrote:

Ok with that, but the original question was about identification as a free action when meeting someone with active spells.

Let's say I have used a fireball on some guy. I notice he suffer very little damage, so he has some kind of fire resistance.
I can have as much Knowledge arcana as I want, but I can't say if it is because he has a ring of energy resistance, fire, he has an active spell or he has some kind of natural fire resistance. Other factors can change that, like "I know he is an inquisitor and he has a flickering aura, so I can identify...

Fireball isn't an active spell effect, it's instantaneous, so the skill would be spellcraft.

If you later, came across the room with the black marks where fireball had been cast, you could attempt Arcana to ID the spell based on the damage it caused. Or rather, to ID the magic that could have done this.

I was speaking of identifying what gave him fire resistance, not about identifying what spell I have cast against him.

Hopefully I know what spells I am casting. :P

Scarab Sages

Diego Rossi wrote:


I was speaking of identifying what gave him fire resistance, not about identifying what spell I have cast against him.
Hopefully I know what spells I am casting. :P

Sorry about that.

That one would challenging with arcana, since their are lots of things that could grant fire resistance. You could probably determine from the blast zone, if your target took the damage, resisted it, or if they dodged the attack entirely. But beyond that, you'd need some method of deducing what they used to resist it. You could make assumptions, and based on those assumptions, narrow down what the target used, but that's guesswork at best.

For example, if you are sure the target is a normal human, and you are that the damage hit them, but that they resisted it, then you'd be aware that they had some degree of fire resistance. That said, it wouldn't be enough to ID their method of obtaining that defense, unless you had more clues.

You could, however, assume the existance of some clues and devise a conclusion based on that.

For example, you could assume that they using a method known to you, and that this method is based on a magic item. You could then scour your memories of such items (arcana) to determine which item they could have that would be affecting this. This would still be an assumption, but it's one you could test by stealing/sundering the similar item that the target was wearing. Like if you determined that their source of fire resistance was likely their armor, you could remove their armor and see if they lose their fire resistance. And if they did lose the fire resistance, you'd have proved that it was caused by the armor.

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