Using Knowledge (Arcana) in place of Detect Magic

[Organite]

I did some brief research but none of what I found here explicitly answered the question I had about the abilities listed in the title.

I got in a rather long debate with a couple of my magus players when they tried to identify a magical aura cast upon a village making use of Knowledge (Arcana) without first utilizing Detect Magic in order to confirm the presence of a magical aura.

Since the villagers were acting strange my players contended that a Knowledge (Arcana) check would suffice for identifying the aura in place and I rebutted that they could only ever suspect there was a aura in place and would never actually know until Detect Magic was performed.
It boiled down to minutia in the definition of "Identify" meaning you needed to know it was there in order to identify it.

Since I had more or less made it obvious by contending the point so fervently that there was indeed a magical aura in effect I let it slide, but made it be known that from there on I would want Detect Magic cast to be able to identify an aura.

You might ask yourself, "why would they put up such a fuss to cast a cantrip?" Well, my genius magus players neglected to take Detect Magic as one of their cantrips...

Anyway, I guess at the end of the day all I want to know is if I am just in requiring Detect Magic in similar scenarios in the future.

[alexd1976]

They can argue whatever they like, the language of the skill does read in a way that could allow for the interpretation they are arguing...

However, declaring the Detect Magic must be used to allow that use of the skill is not only common, but assumed in every game I have played in.

As GM, you make the calls when things are not clearly spelled out. If the player didn't take Detect Magic, that's his problem, not yours.

You could allow him to swap out another cantrip for it if you are feeling generous.

[Create Mr. Pitt]

I actually think Spellcraft is the more appropriate check either way. I do kind of hate that Detect and Read Magic are nearly must take cantrips; I don't like false choices. But these are all calls in the realm of acceptable GM discretion.

[Blakmane]

Your players are incorrect. Knowledge: Arcana is an appropriate check, but they still need to cast detect magic. From the CRB under the skills section, page 101:

"Identify auras while using detect magic - Arcana - 15 + spell level"

[Azten]

Spellcraft is for spells as they are being cast. Knowledge(Arcana) is for active spell effects.

I agree with alexd1976.

[Quandary]

Blakmane's point is correct, 'auras' only are ID'd via Detect Magic,
you can use Know:Arcana to ID an active spell effect WITHOUT caring about the aura (or Detect Magic),
but it has a DC that is 5 higher, and implicitly requires you to already perceive/notice the spell effect,
i.e. visually or potentially by sound, smell, etc., thus shouldn't apply to subtler magics.

[Crimeo]

Villagers acting weird, if an enchantment, is also listed under sense motive as one of the things that skill does. Just to complicate things

[CampinCarl9127]

Organite wrote:

Well, my genius magus players neglected to take Detect Magic as one of their cantrips...

Then they deserve to die via not knowing what any magic is ever. That is literally the only cantrip (other than read magic for spellbook casters) that is 100% required.

Your interpretation is correct, your players are wrong. Tell them to take detect magic or they'll never know what magic is going on around them.

I mean, what caster with 0th level spells doesn't take detect magic? Even ones with divination as an opposed school will take it.

[Arcane Addict]

I'd rule against it. If you cannot perceive the aura there's no way to study it. That said, assuming the presence of an aura in such a situation is valid, especially when a character has Knowledge: Arcana. Of course, you don't have to remind anyone about the possible consequences of making such assumptions...

I do think you handled it well in this instance. You resolved the situation and made a ruling for the future. If your players were merely foolish in neglecting to take Detect Magic, I'd allow them to switch out another cantrip for it. If, on the other hand, they neglected it purposefully because they thought the skill could take its place I wouldn't allow the switch and I'd tell them. Effectively nothing changes but they'll know not to try and pull a fast one on me again.

[Crimeo]

Quote:

if you cannot perceive the aura there's no way to study it

As I understood it, the argument was that they were using the NEXT example down of arcana usage: "Identify a spell effect that is in place"

Which is valid, for something visible like a trap (anyone can see a trap perception so must be normally visible), or a wall of fire or a tiny hut or something. But not I think for spells that don't describe anything that would clearly be visible. Those you'd need to light up their auras to identify them, requiring detect magic.

[ryric]

CampinCarl9127 wrote:

Organite wrote:

Well, my genius magus players neglected to take Detect Magic as one of their cantrips...

Then they deserve to die via not knowing what any magic is ever. That is literally the only cantrip (other than read magic for spellbook casters) that is 100% required.

Your interpretation is correct, your players are wrong. Tell them to take detect magic or they'll never know what magic is going on around them.

I mean, what caster with 0th level spells doesn't take detect magic? Even ones with divination as an opposed school will take it.

Unless there is a magus archetype involved that changes this, all maguses get detect magic in their spell books. The player simply needs to change their prepared spells and they are good to go.

[Arcane Addict]

Crimeo wrote:

Quote:

if you cannot perceive the aura there's no way to study it

As I understood it, the argument was that they were using the NEXT example down of arcana usage: "Identify a spell effect that is in place"

Which is valid, for something visible like a trap (anyone can see a trap perception so must be normally visible), or a wall of fire or a tiny hut or something. But not I think for spells that don't describe anything that would clearly be visible. Those you'd need to light up their auras to identify them, requiring detect magic.

Yes, exactly. I could've been more specific.

ryric wrote:

Unless there is a magus archetype involved that changes this, all maguses get detect magic in their spell books. The player simply needs to change their prepared spells and they are good to go.

And now I feel really stupid!

[Organite]

ryric wrote:

Unless there is a magus archetype involved that changes this, all maguses get detect magic in their spell books. The player simply needs to change their prepared spells and they are good to go.

I'll point this out to them, but both of them showed me their spell books and they didn't have the spell. To their credit it looked like their spell list was generated off of some program so perhaps the program missed it. This is also my first game with Magus players so I'm still trying to get to know the class.

Thanks for the input everyone!

[BretI]

ryric wrote:

Unless there is a magus archetype involved that changes this, all maguses get detect magic in their spell books. The player simply needs to change their prepared spells and they are good to go.

Eldrich Scion, a spontaneous casting Magus. Not very good -- too few skill ranks and until 8th level it can only use Spell Combat for a very limited time per day.

Organite wrote:

ryric wrote:

Unless there is a magus archetype involved that changes this, all maguses get detect magic in their spell books. The player simply needs to change their prepared spells and they are good to go.

I'll point this out to them, but both of them showed me their spell books and they didn't have the spell. To their credit it looked like their spell list was generated off of some program so perhaps the program missed it. This is also my first game with Magus players so I'm still trying to get to know the class.

Thanks for the input everyone!

Make sure you understand spell combat, spell strike, and how it interacts with touch spells. That is critical to understanding a Magus in play.

Here is a good explanation of this that I found helpful.

Expect very spiky damage output. Sometimes the Magus will completely destroy an opponent in one round (spell strike with a critical can cause a LOT of damage), while if they get unlucky the damage will drop to almost insignificant (failing concentration checks and no crits) so be ready for it as a GM. Don't think "that was way too easy" when they get lucky.

[Organite]

BretI wrote:

Expect very spiky damage output. Sometimes the Magus will completely destroy an opponent in one round (spell strike with a critical can cause a LOT of damage), while if they get unlucky the damage will drop to almost insignificant (failing concentration checks and no crits) so be ready for it as a GM. Don't think "that was way too easy" when they get lucky.

Thanks. That guide answered a lot of questions I had especially about Spell Combat and Spellstrike used in sync.

And yea, spiky damage indeed...

[Glorp19]

Hello, one the genius players here. Okay so my dm here is missing part of what I was saying. Also not a magus. I ported over a warmage from 3.5 so we could get some damage output. I'd also like to point out to my friend organite up there that I was hoping one or both of our other spellcasters had dextect Magic so I didn't use my one advanced learning for a cantrip. Usually a fairly reasonable decision.

Secondly a big part of my argument was the fact we are playing a campaign in forgotten realms. The way the use of magic is described in the setting being the core piece here. In forgotten realms the weave is described as a fabric of the world that mages can sense or see to be able to draw magic from it. It also describes large magic effects having a drain on said weave to the point of mages being able to feel it. Now it stands to reason from a fluff perspective two users of the weave would be able to perceive a magical effect.

Sure this lacks some punch in a crunch perspective, but this is where most dms take a stylistic choice to just go with it. Sure at a later time one might lay down a fiat and say. Get detect magic which can be solved by buying an item. Instead we now have a fiat declaring two list based casters with set spell lists unable to sense that magic is going on with out a limited use cantrip. Much as most dms allow basically unlimited use of detect magic which is not an ongoing effect, but this is from a dm that hides loot behind walls and tells you you missed out on it because the dwarf player wasn't there. Too bad so sad, so I don't know what I was expecting in the reasonabitily department.

[Crimeo]

Quote:

Now it stands to reason from a fluff perspective two users of the weave would be able to perceive a magical effect.

"There's some sort of magic here" =/= "Oh hey, that's a charm person spell, cast on a Tuesday, by a man with some lettuce in his beard."

In other words, the fluff you're describing sounds like a spotty, inconsistent version of round 1 of detect magic, only, and not ever necessarily rounds 2-3 on its own.

However I wouldn't ask you to get some cumbersome item or to simply suffer. I would tell you to give up one of your cantrips and replace it with detect magic. The character would definitely have learned it given the GM's description of how the world works, because he should have known how the world works since childhood, but the player didn't until during the campaign, so it should be retconned for the most reasonable storyline AND gameplay.

[Glorp19]

Crimeo wrote:

Quote:

Now it stands to reason from a fluff perspective two users of the weave would be able to perceive a magical effect.

"There's some sort of magic here" =/= "Oh hey, that's a charm person spell, cast on a Tuesday, by a man with some lettuce in his beard."

In other words, the fluff you're describing sounds like a spotty, inconsistent version of round 1 of detect magic, only, and not ever necessarily rounds 2-3 on its own.

However I wouldn't ask you to get some cumbersome item or to simply suffer. I would tell you to give up one of your cantrips and replace it with detect magic. The character would definitely have learned it given the GM's description of how the world works, because he should have known how the world works since childhood, but the player didn't until during the campaign, so it should be retconned for the most reasonable storyline AND gameplay.

Well considering we only needed to know the effect of the spell not spell name or caster, it would have been enough. But I see what your getting at