Traces of Magic as Diegtic Investigation Tool

Fenris-77 · Monday at 10:38 AM

So I'm working on a system agnostic supplement that treats the traces of magic (i.e. casting) as a forensic clue that can be folded into investigations. I have lots of vectors of interpretation, but I'm soliciting suggestions because no one brain can come up with all the ideas.

I'm going to expand a little bit so people can get the gist of what I'm trying to do. There are lots of games out there where investigation and magic are both in play. Call of Cthulhu, most modern urban fantasy, plus a lot of actual fantasy (especially things that aren't laser focused on dungeon play). The funny thing about all those games is that they treat magic like it's not real. Don't get me wrong, the effects are real, but the process of casting spells leaves no trace or imprint on the setting itself. It disappears like dust on the wind (cue the Kansas backing track). So I think there's real value in changing that basic assumption.

What if magic did leave traces that can be read and interpreted (by PCs especially)? My main inspiration here is the Rivers of London novels and the concepts there of vestigia and signare. The first is a magical trace that identifies the magic used, and the second is the magical signature of the person who cast the spell. I'm calling those same two ideas Residuum and Imagos so that Ben Aaronovitch doesn't come after me with a cease and desist order.

The basic idea of the supplement is that I have a whole bunch of random tables that can generate evocative descriptions of residual magic, and a slim set of mechanics that let PCs detect those traces. Plus a whole bunch of ideas about how to tie those two things together in a whole bunch of ways depending on the game you are running.

I've come up with a bunch of ways to deploy this idea in various sorts of games, but system agnostic is hard, so if anyone else has cool ideas I'm all ears. Anything I use will get you a credit in the published PDF. The other reason I posted this idea si that I'd love to have people think about how they'd use the idea in their own games. I'm happy to expand on the mechanic at need. Anyway, I'd love to hear what people think.

Umbran · Monday at 6:41 PM

It seems to me that you end up with the issue that in the end, this cannot be fully system agnostic, as it becomes dependent on the skills/powers/spells the system has in terms of detection and understanding of the imprints of magic on the world.

D&D has an Arcana and Investigation skills, Detect Magic, and Identify... and that's about it. A GM would have to figure out what spells do what in your scheme.

dbm · Monday at 6:43 PM

Ars Magica has the concept of a wizard’s sigil, which is a quirk or flair in all their magical creations. You can sometimes deduce who cast a specific spell (or invented the spell, perhaps) by identifying the sigil incorporated into it. I don’t recall any specific rules for that, however.

I think the composition of a spell, perhaps the mix of magical energy it created by, is also an interesting angle.

D&D has schools of magic and you can often identify the school more easily than you can identify its specific purpose. For example, in the campaign we are currently playing my character (a Druid) wanted to take his staff into the enclave of a neutral / hostile power. While I managed to pull off the Gandalf scam (“would you deny an old man his walking stick”) it was still magical but happened to radiate divination magic since it was a Quarterstaff of Warning, so the door guards let me bring it in. An evocation staff would have been much less likely to be allowed.

Going beyond that, Ars Magica again has 15 different types of magical energy and you can deduce something about a spell based in that. Learning that a spell was Perdo magic might clue you in to whether a specific mage could likely cast it if you know their strengths and weaknesses. Other magic systems similar have the concept of different mixes of magical energy which could be informative if you investigate them.

Byrd · Monday at 7:59 PM

My first question would be: does this game system have any mechanics for tracking by scent?
If yes, how could they be applied and/or expanded?

[Character/familiar(s)/trained animals] + [material components, both before or after use]

Divination (or surveillance) to note verbal or semantic components?
[Echo of the past.]

prabe · Monday at 10:32 PM

Fenris-77 said:
So I'm working on a system agnostic supplement that treats the traces of magic (i.e. casting) as a forensic clue that can be folded into investigations. I have lots of vectors of interpretation, but I'm soliciting suggestions because no one brain can come up with all the ideas.

I'm going to expand a little bit so people can get the gist of what I'm trying to do. There are lots of games out there where investigation and magic are both in play. Call of Cthulhu, most modern urban fantasy, plus a lot of actual fantasy (especially things that aren't laser focused on dungeon play). The funny thing about all those games is that they treat magic like it's not real. Don't get me wrong, the effects are real, but the process of casting spells leaves no trace or imprint on the setting itself. It disappears like dust on the wind (cue the Kansas backing track). So I think there's real value in changing that basic assumption.

What if magic did leave traces that can be read and interpreted (by PCs especially)? My main inspiration here is the Rivers of London novels and the concepts there of vestigia and signare. The first is a magical trace that identifies the magic used, and the second is the magical signature of the person who cast the spell. I'm calling those same two ideas Residuum and Imagos so that Ben Aaronovitch doesn't come after me with a cease and desist order.

The basic idea of the supplement is that I have a whole bunch of random tables that can generate evocative descriptions of residual magic, and a slim set of mechanics that let PCs detect those traces. Plus a whole bunch of ideas about how to tie those two things together in a whole bunch of ways depending on the game you are running.

I've come up with a bunch of ways to deploy this idea in various sorts of games, but system agnostic is hard, so if anyone else has cool ideas I'm all ears. Anything I use will get you a credit in the published PDF. The other reason I posted this idea si that I'd love to have people think about how they'd use the idea in their own games. I'm happy to expand on the mechanic at need. Anyway, I'd love to hear what people think.

Since you mention the novels, I'm going to ask if you've read the Rivers of London TRPG. It does not obviate what you're trying to do, by any means, but you might find it helpful.

Fenris-77 · Tuesday at 4:02 AM

prabe said:
Since you mention the novels, I'm going to ask if you've read the Rivers of London TRPG. It does not obviate what you're trying to do, by any means, but you might find it helpful.

I very specifically didn't read it, but I will.

Fenris-77 · Tuesday at 7:18 PM

Umbran said:
It seems to me that you end up with the issue that in the end, this cannot be fully system agnostic, as it becomes dependent on the skills/powers/spells the system has in terms of detection and understanding of the imprints of magic on the world.

D&D has an Arcana and Investigation skills, Detect Magic, and Identify... and that's about it. A GM would have to figure out what spells do what in your scheme.

I'm going to do conversions for some of the major systems in a appendix. Very little RPG design is truly system agnostic. This will be broadly so for most OSR games as I'm writing it.

Detect magic isn't problem as it's not designed to detect anything that I'm proposing, and the mechanics I'm doing don't overlap with what detect magic does (on purpose). Same with identify.

Koloth · Tuesday at 7:54 PM

Some thoughts and questions:
How long do the traces stay around? Minutes? Days? Forever etched in local matter?
If Spell B is cast in the same spot 2 days after Spell A, does B overlay A? Or can both be found?
Is it possible that the leavings of Spell A could interfere in some way with Spell B? Cause a misfire or combine in some way to create a new and exciting spell?
There are probably one or more professions around investigating spell use and spell forensics.
Can spell forensics be used in a court of law?
Can spell traces be cleansed?
Might be business around cleaning up after spell use. Perhaps the new owner of a manor doesn't want traces of the spell(s) used to murder the former owner left in the place.

Byrd · Tuesday at 10:56 PM

Koloth said:
Some thoughts and questions:
How long do the traces stay around? Minutes? Days? Forever etched in local matter?
If Spell B is cast in the same spot 2 days after Spell A, does B overlay A? Or can both be found?
Is it possible that the leavings of Spell A could interfere in some way with Spell B? Cause a misfire or combine in some way to create a new and exciting spell?
There are probably one or more professions around investigating spell use and spell forensics.
Can spell forensics be used in a court of law?
Can spell traces be cleansed?
Might be business around cleaning up after spell use. Perhaps the new owner of a manor doesn't want traces of the spell(s) used to murder the former owner left in the place.