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I know that one can use the spell "Detect magic" to find out whether any spells are being cast or active. But is it also possible, using some spell, feat or whatever, to find out whether a person is able to do magic (a spellcaster)? If that is the case, how does it work - for example, can I just look around and "see" all spellcasters, or do I have to look at each person in detail, one at a time? Are there differences in the "discoverability" of different spellcasters such as divine, arcane...?

Note that I'm not interested in reading the person's thoughts or looking for clues in the person's equipment or behaviour.

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Actually, I ask because in designing my own RPG, I want to get an overview of how other systems handle this. So the edition does not really matter, please answer for any one or all ;-) – Jens Bannmann May 14 '12 at 20:37
Are you interested in what other systems do? Earthdawn and Shadowrun have mechanics that let you examine your subject astrally to try and learn about their magical capabilities. Lots of other games will have similar mechanics to learn the capabilities of other characters. – Simon Withers May 14 '12 at 20:47
Simon: thanks! I didn't know about how it is handled in Earthdawn; I play Shadowrun myself. Mostly I want to know about D&D, though. – Jens Bannmann May 14 '12 at 20:51
This has a lot to do with the fiction of your setting. It's more about how magic works in the setting of your game (I take it you have at least an implied setting) than about game mechanics. Or rather, the mechanics should support the fiction, rather than the other way around. – gomad May 14 '12 at 22:02
up vote 11 down vote accepted

In D&D there's no way to know that a character is a spellcaster apart from witnessing them using spells or some more subtle tell-tale of behaviour or dress. A wizard could easily masquerade as a commoner by choosing to not to cast any spells, hiding their spellbooks, and not bothering to re-memorize spells. A cleric could trivially pass for a mundane person or non-spellcasting priest by just not performing miracles.

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Some D&D settings, most prominently Dark Sun, are built on the assumption that you can't determine if someone is a mage. Imagine if Templars could cast a spell to detect a Preserver or Defiler? – YogoZuno May 14 '12 at 23:18
Unless I'm misremembering, the 'Greater Arcane Sight' spell that existed in certian editions did allow you to detect the highest-level spell a spellcaster had prepared. Admittedly, it would fail if the caster had no spells prepared, but in a very real sense that means that the target isn't a spellcaster. Not at the moment, anyway. – GMJoe May 15 '12 at 2:56
If you are playing 4e a perception check (against how they are dressed, how the act, etc) would seem very appropriate or an arcana check if the player is trained in arcana along the same lines. – Joshua Aslan Smith Jul 30 '12 at 19:25
"A cleric could trivially pass for a mundane person or non-spellcasting priest by just not performing miracles." If they're aligned, the aura they produce might give them away; it'll be much stronger than a typical person's. (There are also some ways to determine how many HD someone has, so by comparing aura strength to HD you can determine that they're a cleric or something similar.) – starwed Jan 19 '13 at 19:41
@JoshuaAslanSmith to be fair, even in 3.5, your DM might allow your character to make a jump in logic to decide that the person walking down the street wearing minimal armor, without any substantial weapon, with a funny little traveling pack at their waist and a very egotistical and superior expression would be a mage. – acolyte Jun 13 '13 at 20:53

Sort of. The 3rd level sorc/wiz spell Arcane Sight (3.5) allows you to

determine whether [a creature] has any spellcasting or spell-like abilities, whether these are arcane or divine (spell-like abilities register as arcane), and the strength of the most powerful spell or spell-like ability the creature currently has available for use.

Note that if they've already used these for the day, or used their strongest - this could be terribly misleading. The spell lasts for a minute per level and lets you focus on one creature within 120' as a standard action.

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As SevenSidedDie points out, in DnD it is generally easy for a spellcaster to hide the fact they are spellcaster if they wish.

With that said, when they aren't hiding the fact, then the hints will often be fairly obvious. Wizards will often have pouches with spell components and if travelling in a group may be the only one without armor in an otherwise heavily armed and armored groups. Clerics will generally be proud of their faith and likely have the holy symbol worn openly and may even decorate their equipment with other signs of their faith. Of course, it is possible for someone wanting to seem powerful to masquerade by wearing symbols of faith or pouches of components even if they can't even cast a cantrip. But it is still a decent indicator.

Now, if you want to look outside of DnD for somparison when making your own game, it is a fairly common trope for certain types of magic users to be able to see auras and for those auras to display signs of magic use. Shadowrun has this well developed and Vampire: The masquerade used a similar system as a power under the Auspex Tree.

It would also be reasonable for use of magic to have side effects that show its presence on the user. The expanded universe for Star Wars has a concept of "Dark Side Corruption" where extended use of the dark side will physically disfigure the user. While certainly not magic users per say, the mentats in the Dune series tended to be addicted to Sapho which would stain their lips purple.

It might also be the case that very powerful magic users would radiate the energy they are most attached to. A fire wizard might always be physically hot and possibly glowing. Mage: The Ascension in its high level supplement discusses this happening for mages that reach very high ranks in a sphere, especially those that become "exemplars".

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Multiclassing and Dual-classing muddy the waters here. A guy wielding a sword but not wearing armour, for instance, could have just gone into combat without his armour, or may be a fighter/mage of some sort. In the same manner, if one wanted to masquerade as a mage, one could dress in a robe and carry spell components. I've also seen players have their character masquerade as a different type of spellcaster - a mage pretending to be a cleric, for instance, and using cantrips to pretend to heal. – YogoZuno May 14 '12 at 23:20
@YogoZuno All true, it is an imperfect indicator, but most indicators in reality are. Their attire and what they are carrying remains a strong indicator though. – TimothyAWiseman May 14 '12 at 23:40

It seems like people here have already mentioned some interesting RP-oriented and flavorful answers. However, in case you seek an actual in-game way of finding out whether someone is a caster... Well you can always try the Arcane Sensitivity spell from The Shining South, I bumped into it a few days ago.

Granted, it only works for arcane magic, but it's pretty much what you want. Plus it kinda makes sense, divine magic is all about faith, not the innate Gift a wizard/sorcerer or any other arcane caster has to be born with in order to manipulate the Arcane ;) .

The above is for the 3.5 version of the game, but it can easily be adopted in 2E and perhaps even 4E with some effort.

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I second the call to have this ability tied to the nature and source of magic in your campaign. In Ars Magica, for instance, all magi have an innate power called The Gift which allows them to use magic. Other magi nearby can feel the gift, as can animals, who usually react negatively, unless you have the Gentle Gift virtue, which can allow you to pass for a non-wizard.

I think any such ability in your own game should likewise be determined by what magic is. Is it a natural force that can be manipulated, almost mechanically, by repeating rote phrases and gestures? In that case it's not an inherent trait in a caster that can be detected, but is more of a skill. In that case, I'd allow a Perception check by someone deeply familiar with spellcasters to detect the effects of magic on the caster - is that a smudge of sulfur on his fingers? Are those singed eyebrows? That feels like a wizard to me!.

However, if it's an intrinsic aspect of the character, like Sorcerers in D&D, then a particular spell could be developd to sense it. The level of that spell would, again, depend on the kind of setting you're trying to create. High-magic world where spell-casters are common? Probably a low-level spell.

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In most systems armor prevents arcane spellcasting, this can be used as a clue. Of course, if the magic user is not battle-ready but tries to hide or use a disguise, it's not that simple.

However, if you encounter a group of armed adventurers, you can usually spot an arcane magic user by the equipment.

Even in other cases, there might be clues still derived from the armor penalty to arcane spells. Even if an arcane spellcaster tries to fool you by disguising as a fighter, there are not that many fighters who are not muscular. You can usually recognize if someone dressed as a peasant isn't one: peasants have rough skin on their hands as they work on the fields.

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If you're designing your own RPG you'd better take a step back.

Ask yourself why it's important that characters have a way to detect spellcasters. Is it ok that both the PCs and the NPCs can do that? Don't reason in terms of world logic yet. What do you expect from this mechanic to behave in your game? Does it serve some purpose or is it just an obstacle?

Try telling me the episode that convinced you it was important in a RPG to have this feature.

Hopefully I'm gonna get confident with the site structure and be back to answer you.

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I'm not convinced that it needs to be possible. I had just noticed that different systems handle it differently, and since my own system does not come with a setting, I was interested in what could be the "mainstream" answer to the question. For what it's worth, for now I decided that it's not possible, but will probably not add an explicit rule against detection. This way, each group can decide according to taste and setting. – Jens Bannmann Aug 6 '12 at 21:10
I strongly advice you against letting thee group decide, unless you clearly state this in the rules. It makes for different experiences with the same game and this does not help the game get its distinct flavor. Keep in mind that good game design has all the rules working toghether to get some specific experience. Is your game about doubt, fidelty and such moral issues? Probably prohibited magic, flashy but impossible to detect when not used is great. "You should have told me before!" Imagine the same game with different rules: Magic is no more important to the plot, why is it there? ;) – Zachiel Aug 8 '12 at 8:07

protected by Brian Ballsun-Stanton Jun 13 '13 at 14:48

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