@Reaver: I honestly don't know, so have to ask: has it anywhere in fluff or rules been mentioned, that you can summon a specific spirit just by having seen his signature (not even its live aura)?
If you combined this with the assumption that the universal memory is not only a "this a guy is bad, this one treats you well" but real, shared memories, that would be extremely powerful.
The only way I know to summon a specific spirit is knowing its true name. But I haven't read every book.
This is difficult to answer. Yes there has been mention of this both in fluff and in the books over the history of the game and novels. (Burning Bright comes to mind off the top of my head). How true the fluff is to canon? That I can not say.
But I will point you to the only firm part of 5e that I have: (and It will take some creative thought to follow me/this)
Page 300 core book, 5e. Red box at the bottom of the page :
The exact nature of spirits, how the spirits who are summoned are selected, and why they look the way they do is
a subject of much debate among Sixth World magical scholars. What is clear, though, is that summoned spirits tend
to appear in a way that is appropriate to the summoner’s tradition. This could be because the summoner’s magic helps
determine what spirit is summoned, or the spirit could be trying to gain the favor of the summoner by appearing in a shape
the summoner expects. Most spirits seem to like being on Earth, but the exact reasons are unclear and the spirits are not
keen to share any information.
Now I bolded some parts in there to high light my thought pattern (so follow me here).
How a spirit is chosen has rules/requirements. Some of these are tradition based (so a mage detective couldn't summon a shamanic Spirit, granted), but others of these area mystery, but it seems clear that the summoner in fact has a choice in the matter, even if that choice is the sub-conscious level. This is why your Fire elemental appears as a pillar of fire, Steve's looks like a Phoenix, and mine like a little red fire truck....
As long as the summoner matches the tradition, and knows the aura of the spirit, it stands to reason that, he could attune the summoning to the spirit he wants in question. Note, this in no way means that
that spirit responds... merely that he can try to summon the spirit in question. (After all, he does not have the spirit's true name (not the name it tells it summoner, its TRUE name.) and thus can not FORCE the spirit)
As for the knowledge of spirits, While I have not read the new Grimoire yet, established history of SR does confirm this (to the level of each GM's choosing) most clearly and recently in the 4e street magic book under the discussion of Spirit Knowledge..... While they leave the door open for GM interpretation, They make a VERY strong case for more a hive-mind-shared-history-memory ability of Spirits, as Spirits that shouldn't possibly know of some things, actually do... But how this ability works, what it's limits are, are only known to Spirits (and the GM).
And this too is supported in the fluff and novels as well (and with the same shaky claim to canon as I mentioned before). Once again Burning Bright springs to mind. (this could be of course cause I was re-reading Bug city recently).
the other side of the argument is simple logic and deduction. Again follow me here
"If you can think it, Someone has done it" is a pretty standard saying in the RPGs... and it's a standard saying for a good reason.
Game worlds are supposed to be actual functioning worlds that are bound by rules and laws, and have a natural working order to them. Now, Game Designers are both limited by page space, their own knowledge, and their own creativity..... Now this is a problem for all games, is that the designers simply CAN NOT write down a rule for every single little thing. For one, not one would buy the books, and they would fill a library...not to mention they couldn't write it all down to begin with. Heck, go to your local library and look around. Right there is the history and workings of OUR world... yet no one goes there anymore... (damn Wikipedia).
So that leaves the GM to apply the "If you can think it, Someone has done it" axiom.... and the other, silent axiom that is "And they have a counter for it". In short. Every way a character thinks they have pulled of the perfect crime... Someone else has figured it out too and done it. And Law enforcement has a counter for it. (even if that "counter" is an after the fact investigation.). Their belief that they have "pulled off the perfect crime" through an exploit of perceived rules is wrong. (at least from the perspective of this Axiom) And while the rules may not come directly out to say one way or the other on a given topic, the GM should step back and ask himself some baseline questions:
What exactly is the person trying to do/say?
What are the possible consiquences of that line of action for the current game?
If everyone can do this, what would be the world consiquences of said actions on the world (economically, socially, etc)
How and why would what the person is saying/doing going to work....
And finally, just how original is this action (in the game world). The less original it is, the more likely it is there is a counter for it... Even if that "counter" is after the fact.
In this case, The main action is "Summon a Spirit, send on rampage".
Well, this is not very original. In fact, I bet every single person that read the spirit section thought of this. Every. Single. One. So it stands to reason the law enforcement would have some sort of counter to this.
Why? Cause if there isn't, the game world breaks down.
If all a mage wanted to do to get away with murder was summon a spirit, and have it kill the person and there was NO WAY to trace it back to the mage, society would go into a panic right quick. Not to mention that there would be a LOT more murders out there. (Think about it.... you are basically saying every mage on the planet has an "I don't like you. DIE!" button....) this would be priority number one for EVERY security, military, and law enforcement agency on the planet.... Some one out there, much smarter then you, or me, or Billy-the-Four-eyed-rules-lawyer-you-beat-to-near-death-every-week-with-a-phonebook, could ever be figured out a way.... Cause it just makes sense. For the game world.
Now, that doesn't mean that a runner who uses a spirit to bump someone off
is going to get caught. Merely that there is a
chance that he could get caught. IF he does, or does not, get caught is still up to the GM, the dice, and the RP.... and is not an absolute "get away scott free" if he uses a spirit to commit his crimes.
