Modifying detect magic for use as a pasive ability.

[Feddlefew]

Background: My DM has given everyone the option of gaining one powerful ability with some pretty hideous drawbacks. Since I'm making an new character, we need to come up with something.

I wanted to go with permanent detect magic for the beneficial side of the ability, but detect magic normally works as a 60' cone in front of the caster. How broken would it be to change that to a N diameter radius around my character, kind of like listening for magic instead of looking for it? Would there also need to be some kind of check pick out certain things, kind of like a magical listen check?

[jedipotter]

Sounds more annoying then broken. A ''passive'' detect ability is always annoying. It's like making a ''detect magic listen check every five foot step''. The amount of ''passive rolls'' will take up huge amounts of game time and be very annoying.

Consider that past 5th level or so, everyone will have magical spells or items on them. So every time your character encounters anyone you'd need to make the check. Think like you'd walk down a torch filled hallway and have to stop the game and make a check at every single everburing torch.

You are far better off just keeping detect magic as ''I can turn it on and scan the area, but can't leave it on''.


But then too, ask yourself what do you really want to detect magic for?

[Fenryr]

Pathfinder has an option like that. By expending Race Points you may have Constant Detect Magic and you have the First Round of Detect Magic all the time. To get the Second and Third Round you use your Standard Actions to focus on the auras.

Now, changing it to N diameter is quite better than the cone. If you wish to "listen" to magic perhaps Arcane Sight (http://www.d20srd.org/srd/spells/arcaneSight.htm) is a better option.

[Feddlefew]

Sounds more annoying then broken. A ''passive'' detect ability is always annoying. It's like making a ''detect magic listen check every five foot step''. The amount of ''passive rolls'' will take up huge amounts of game time and be very annoying.

Consider that past 5th level or so, everyone will have magical spells or items on them. So every time your character encounters anyone you'd need to make the check. Think like you'd walk down a torch filled hallway and have to stop the game and make a check at every single everburing torch.

Do you play/run a game where players have to roll a listen check every time there's any sound in the vicinity? It'd be more like the DM tells me "You notice X" when describing the surroundings, and maybe a check for something subtle or hidden. I see the difference between noticing a magical effect is there and attempting to figure out what it is as being the same as between "There are two people talking in the corner." and "You attempt to eavesdrop on the two people talking in the corner."- the first case is passive, the second case is active and has a chance of failing.

@Fenryr- Yeah, Arcane Sight reads more like what I want, although I don't think the DM will let 120 feet fly at low levels. I was thinking that as my character gains levels the radius expands, since the fluff is that they've had their arcane magic tapped/removed by another entity, and they feel magical auras through the resulting hole in their being.

[Psyren]

This is pretty easy to do, especially since permanent detect magic is already a thing in both 3.5 and PF (i.e. Permanency + Detect Magic.)

As far as your "all-around-magic-vision" suggestion, the easy way to do this would be to have magic items outside your field of view emit a chime or sound instead of (or in addition to) the "magic glow" that only you can hear. That tells you where to turn your head, at which point you see the glow. Anything that blocks line of effect or divinations (your choice) can block the sound.

[Mr Adventurer]

Just have Greater Arcane Sight instead.

[Der_DWSage]

To answer your original question:That sounds like a pretty nifty ability, honestly. If I were your GM, I'd say go for it.

That said...I'm curious what the power level is on the other abilities your party will be getting, because this is a pretty low-power thing for the 'massive drawback' you were talking about initially. You may want to upgrade this, since as people have mentioned, it's an easily-copied thing with Arcane Eye + Permanency. You might pitch it to your GM as a slowly maturing ability, instead.

1st level:As Detect Magic, 60 foot cone only.
4th level:60 foot radius, rather than cone. Can use senses other than sight to detect magic, but not identify the exact spell.
7th level:Still able to detect magic with other senses, but vision upgrades to Arcane Sight.
10th level:Can now use Detect Magic within line of sight with no regards to range, but cannot identify spells until with 60 feet.
13th level:Arcane Sight becomes a 60 foot (Or 120 foot) radius.
17th level:Constant True Seeing effect.

...Cutting down the level progression to fit your campaign, of course.

[Psyren]

I would give Analyze Dweomer instead of True Seeing as the "capstone" - letting him instantly identify spells, items and even suss out cursed items at a glance.

[Feddlefew]

True seeing doesn't really fit with the theme. Permanent Analyze Dweomer sounds amazing, but the DM might not want me to have that as a permanent for obvious reasons. I also really want a 360 degree field, since I kind of envision it working like hearing does. I do like the idea of it getting upgraded in more ways than just range as she levels up, but no one else got something which gets more powerful as they level, just something that they'll be able to use better.

For reference, the monk received a magic blindfold which gives them blindsense and tremorsense (the former is to a farther range than the later) on top of their regular vision. The draw back is that if it's ever removed, they're permanently blinded and no magic (aside from divine intervention) will allow them to "see" again, including ones which would give them sight-like abilities. He's the only person who definitely knows what his drawback is right now, because no one's tripped there's off and the DM made it clear in game what would happen to the monk to deter shenanigans.

In comparison, permanent loss of a few weak racial SLAs, a domain power that's not going to see much use, and possibly unleashing an outsider* into the world in exchange for a slowly-growing radius of arcane sight seems like a good deal. The campaign main enemies all have SLAs they use, and the DM tends to give important enemies minor magical items or buffs, so in the meta it's going to be very useful for us. If the DM thinks the drawbacks aren't sever enough, I'll point out that my character probably looks rather strange under magic-detecting effects.

*Outsider has vested interest in my character staying alive, since if she dies, they get booted out of reality.