Detect Magic--what counts as magic?

[PhoenixPhyre]

I'm writing a blog post on a theory of magic for 5e and ran across an oddity. The spell detect magic is not specific as to what counts as magic. As such, it seems up to the DM to decide what counts. So how do y'all rule this one? Spells/items only? Residues of past rituals? Non-spell effects (life drain from certain undead comes to mind)? Play it by ear?

For reference, here is the entire text of the spell from the SRD:



1st-level divination (ritual)

Casting Time: 1 action
Range: Self
Components: V, S
Duration: Concentration, up to 10 minutes

For the duration, you sense the presence of magic within 30 feet of you. If you sense magic in this way, you can use your action to see a faint aura around any visible creature or object in the area that bears magic, and you learn its school of magic, if any.

The spell can penetrate most barriers, but it is blocked by 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or dirt.

[Kane0]

Yeah it's pretty solidly in 'ask your DM' territory, but spells and magic items are pretty much a given. It would be plausible to add residual/passive magical effects as well, such as some always-on warlock invocations or an EKs bonded weapon.

Edit: It would be funny to see if a monk glows though.

[mephnick]

It hasn't come up but does always on detect magic completely ruin illusions? Like if I had a BBEG based on illusions is one warlock player going to destroy the campaign?

[PhoenixPhyre]

Yeah it's pretty solidly in 'ask your DM' territory, but spells and magic items are pretty much a given. It would be plausible to add residual/passive magical effects as well, such as some always-on warlock invocations or an EKs bonded weapon.

Edit: It would be funny to see if a monk glows though.

Heh. I actually noticed it in relation to that. If, as the PHB says, the Weave permeates everywhere (except dead magic zones), then if the spell really detected all magic, everything would glow, since everything is in contact with magic. And monks, paladins, anyone with spell slots, etc. would light up, making the spell useless. So it has to be less than that, but what?

I have a warlock with it at will (and boy does he use it). As a result, and as a result of wanting to give them more information, I have houseruled that anyone with a magical connection (can cast any spells, even from racials) can feel the presence of strong magic (as in "the hairs on the back of your neck prickle"), but detect magic and possibly an arcana check are needed to get more specific information or localize the effect.



It hasn't come up but does always on detect magic completely ruin illusions? Like if I had a BBEG based on illusions is one warlock player going to destroy the campaign?


Note that it's not always-on. It's at will. It's still a concentration spell (so no hex) and requires V/S components and an action to cast. That limits it quite a bit. One way to counter-act it is to be smart about the illusions. Namely use them everywhere, even covering totally normal things. It's the purloined letter approach.

[Puh Laden]

Anything magical that is not innate. (As opposed to ki, or else or all life would be detected and that's obviously not the intent.)

For me, this generally means, spells, magic items, and non-spell magical effects such as curses. Generally, even for magic items and non-spells, I'll try to match it to a school of magic, though I might try to tell them that it's a weird sort of that school or a blend of two schools. For example, someone freshly cursed with lycanthropy might have an aura of transmutation and necromancy about them -- until the transformation becomes permanent and thus innate.

[Kane0]

So, active effects then? Like a person that has spell slots or ki doesn't register, but having a spell (including ones usable at will) or magical effect (eg Witch Sight or an EKs bonded weapon) show up as normal. Seeing residual leftovers of effects that have ended is definitely up to the DM.

[PhoenixPhyre]

So, active effects then? Like a person that has spell slots or ki doesn't register, but having a spell (including ones usable at will) or magical effect (eg Witch Sight or an EKs bonded weapon) show up as normal. Seeing residual leftovers of effects that have ended is definitely up to the DM.

Having a spell active (either concentration or not) certainly counts. I'm not sure about Witch sight or the bonded weapon. For the first, it seems an innate effect, not an active effect. For the second, my head Canon is that the magic is only active when it's used to summon the weapon. That's not firm though.

[RareSwordfish]

As a DM, I usually have it used in a manner that shows an active magical effect. So for example, if someone has used polymorph on something and is concentrating on it, you could tell using detect magic. If said spell happened to be a true polymorph, then once the spell becomes permanent, you would no longer be able to tell. Also, you would be able to detect a curse, spell, or magic item, or whether or not the soup is secretly magic poison (don't eat magic poisoned soup, kids). It really makes sense if you think of it like detect ACTIVE magic.

[PhoenixPhyre]

As a DM, I usually have it used in a manner that shows an active magical effect. So for example, if someone has used polymorph on something and is concentrating on it, you could tell using detect magic. If said spell happened to be a true polymorph, then once the spell becomes permanent, you would no longer be able to tell. Also, you would be able to detect a curse, spell, or magic item, or whether or not the soup is secretly magic poison (don't eat magic poisoned soup, kids). It really makes sense if you think of it like detect ACTIVE magic.

Doesn't the bold section step on the toes of detect poison? I'd probably rule that unless there was an active spell on the soup (or soup-bowl, think explosive runes on the bottom :smallbiggrin:), even a magically-created poison wouldn't ping detect magic.

I think there's a consensus so far as to active spells and spell-like effects (items certainly, curses and other spells that just aren't in the PHB almost certainly). Good that's comforting because it works well with my draft theory of magic.

[RareSwordfish]

Doesn't the bold section step on the toes of detect poison? I'd probably rule that unless there was an active spell on the soup (or soup-bowl, think explosive runes on the bottom :smallbiggrin:), even a magically-created poison wouldn't ping detect magic.

You're right, went against my own explanation. Unless said person was currently concentrating to make that soup magically poisoned (or explosive :smallwink:), you would not be able to see it with detect magic.

[PhoenixPhyre]

You're right, went against my own explanation. Unless said person was currently concentrating to make that soup magically poisoned (or explosive :smallwink:), you would not be able to see it with detect magic.

Ahh. We're in agreement. Great!

[Slipperychicken]

My opinion is to count non-innate spells and spell-effects as magical. Innate effects count only if they're stated to be magical. A pixie's invisibility would ping detect magic (it's magical), but an invisible stalker would not (it's made of air, not magic).


Heh. I actually noticed it in relation to that. If, as the PHB says, the Weave permeates everywhere (except dead magic zones), then if the spell really detected all magic, everything would glow, since everything is in contact with magic. And monks, paladins, anyone with spell slots, etc. would light up, making the spell useless. So it has to be less than that, but what?

I was under the impression that the Weave was just an omnipresent framework that people can use to create magic, rather than magic itself. That said, the weave is not going to be the lore for every campaign.

[Kane0]

Could you imagine if Jedi had this problem every time they tried to Detect Force?

[Starman973]

Personally here is what I would do. the more subtle the harder to detect to figure out what they a detecting with an arcana roll.
Target Number 10 <--Active spells and concentrations effects.
15 <--magic items, (still need identify for in what way the item is magic) Innate abilities active Warlock eldritch evocations and Ki effects.
20 <--You can tell who in the room is a caster and if they have a spell focus
25 <--Can tell about any spell that took longer than a minute to cast in the area about a week ago
30 <--You know about any concentration spell cast in the area in the last month.
35 <--You can detect any ripple across the fabric of reality no matter how small in the last season.

[Millstone85]

I was under the impression that the Weave was just an omnipresent framework that people can use to create magic, rather than magic itself.It is an omnipresent framework that people can use to access magic, which is also everywhere. Well, to access "raw magic", and the Weave itself is "a fabric of magic", so my understanding is that it is the domesticated part of magic.

The sidebar actually gives detect magic as an example of a divination spell that would "glimpse the Weave", so my guess is that it is looking for something in the Weave, like traces of manipulation, and would indeed ignore both the Weave itself and raw magic.

[Talamare]

Personally here is what I would do. the more subtle the harder to detect to figure out what they a detecting with an arcana roll.
Target Number 10 <--Active spells and concentrations effects.
15 <--magic items, (still need identify for in what way the item is magic) Innate abilities active Warlock eldritch evocations and Ki effects.
20 <--You can tell who in the room is a caster and if they have a spell focus
25 <--Can tell about any spell that took longer than a minute to cast in the area about a week ago
30 <--You know about any concentration spell cast in the area in the last month.
35 <--You can detect any ripple across the fabric of reality no matter how small in the last season.


Detech Magic is a type of Sense, similar to hearing or tasting.

Arcana would NOT be appropriate here.
Arcana is a use of your knowledge in the Arcane.

The most appropriate would be a Perception Check, but screw Perception Checks. It's already overtly spammed.
Point is, your change helps 1 Caster, and Screws like 7 Casters.