So, I know this has been discussed in the SR3 forums a few times, but now I want to know how it applies to SR4.
The Astral Chameleon positive quality affects the character's astral signature, and nothing else. It says:

Well an Adept using a weapon focus would definately leave a signature whenever they activate the weapon and use it.

I would also surmise that any of the boosted powers where you have to roll for drain would leave a 'ghost image' of the adepts form for you channel more mana than usual to empower yourself.

I think that adepts should leave minor signitures when ever their powers are used heavily (ie after heavy firefights). Or maybe they should generate on that build up over time, so if they hide in place for a while they build one up.

I point from sota 64 that may be relevant is the idea that adept powers only kick in properly when needed, providing an extra boost in extremes, this is why they tend to be hard to pick up astrally. Not sure how to rule this, maybe they leave a sig when they hit five or more successes on a test using an enhanced ability.

BTW its past 3am here in blighty so I am just throwing out ideas.

In SR3, I'd say killing hands left a tell-tale, as would distance strike, in SR4, same basic thing. however I doubt kinsetics would leave a residue ont he folks interacted with, as your screwing with them through their perceptions, but if you stood in one spot too long, maybe...

I suppose I am of too minds.

But the primary one seems to make me think that an Adept would leave a signature whenever he uses his powers, voluntarily or otherwise, though it may be strong or faint.

For instance, if an Adept with killing hands hits someone, but does not have the hands activated(opts for stun) there is no signature. Then he hits someone else with his KH and leaves an astral mark.

Also, an Adept with Mystic Armor does not leave a signature until it activates. In response to an attack. Same with Spell Resistance.


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The other mind seems to feel this would make adepts so much easier to track, and I'm unsure if that fits or not.

I'm of the belief that an adept would only leave an astral signature when activly using their power or in the case of things like armour, actually being used.

Otherwise they would leave a signature whereever they went.
Which seems a bit crap really.

Agreed NightHaunter, from a playabilitiy POV. If the benefit of a power influences something in the game, or it the power was explicitly activated (like Boost Attribute) it leaves some sort of signiture. Like an Adept with Mystic Armor getting shot and using that armor to soak the damage. Otherwise the powers run quiet.

So all powers leave a signature, but only when they're used? I can see the logic, but I still would lean to some powers leave a signature, but only when they're used. Otherwise, what about enhanced perception? They only leave a signature when they're looking at things? Or an enhanced (not boosted) attribute. These are things that are always in effect. However, I definitely agree with killing hands leaving a mark, and certain other powers. But that still leaves me with a large grey area in the middle where I can't decide.

Without getting the book out yet, I'd say:

Spellcasting and conjuring leave signatures impressed upon the area affected. Foci contain signatures. Adept powers, since they're "non-mana-based," do not leave signatures.

I'd have to look up the relevant book quotes to be satisified with that answer, though.

I'd sday that adepts don't leave a signature behind.... there is no game mechanic for it nor any mention of it. ANd I don't like making up new rules just to crock a character class. Besides, spell signatures usually stick around mainly on what they were cast on.... does the heal spell I cast on my buddy stay on him or the place that I cast it?
I think the confusion arises because the astral beacon mentions signatures, but the astral beacon flaw also applies to attempts to astrally assense the character as well (just like its opposite, astral chameleon.)

But there are some powers that an adept really would be using all the time. (or for very long periods of time)
Enhanced Perception. Adds dice to ALL perception tests. Actively used whenever the adept is aware of their environment.
Improved Physical Attribute. Arguable. I could see arguments for this being in effect all the time or only when needed.
Improved Sense. Many improved senses would be active all the time. Some, such as sound dampening, might only kick on when needed.
Kinesics. Arguable. I think, whether the GM is actively asking for rolls or not, kinesics should always be in effect, because the adept is always preternaturally conscious of their body movements as well as others'.
Pain Resistance. Anytime the adept is wounded they're leaving astral signatures everywhere they go?
Rapid Healing. Same as pain resistance.

I don't like the idea that any of the above powers cause an adept to leave an astral signature everywhere they go.
It seems to me that most powers should not leave a signature.
The only ones that really leave me with doubts are Attribute Boost, Killing Hands, and Critical Strike.

I'd say, most powers do not leave signatures, as they run at a lower mana than the quicker spells do. They might, if the adept stays in one area for longer than a day or 12 hours or what have you, of a force equal to the number of time increments he lived/stayed in the area (however much you might set it to, likely stronger adepts build signatures faster).
Activated powers, such as the boosting, critical strike, and killing hands powers leave a signature. How much is likely different, but perhaps the best way of doing it is to use the number (or fraction) of power points used. Likely just double the power point cost to get the force of the signaure it leaves behind. Round up.

edit: Took out missile parry. I just woke up.
And if powers are used in conjunction, add their costs together for the force.

When it comes to astral signatures, I would think that anyone would leave one but it would depend on conditions.

Example, someone who is in great fear, great joy, sex, highly concentraiting such as sneaking or working on a work problem that casues stress, somthing violent happens in a area, magic is activated, etc.

When it comes to adepts, I would think it would also depend on if a ability is active or a passive ability.

Enhanced perception/abilities, senses, spell resistance, looking astraly (I consider that passive),etc are passive in nature

Spell casting, active foci, killing hands, boosting a ability, spell defence, etc would be active in nature and leave trail/sign behind.

I really don't think astral sigs should just be realated to magicaly active people, but as I explained in my opening. This in turn would give those who are a psychic detectives a much needed use.

They would be able to read an area depending on how good they rolled vs how much time went by vs how hot the site was with activity. And of course when the event is over and the perps are long gone, their trail would only leave a good trace if it was a running combat.

If they escaped and were running silent, the trail would fade quickly till it was nothing.

This can give much roleplaying additives. Maybe some people have the ability to read the area and track a running fight but once the situation goes cold (fight breaks off, they are no longer able to be tracked but sombody might be able to gather some info just as a tracker would till somebody started walking on rocks or in a stream.

Get the astral flavor if you will of who and what was going on to a degree.

It would give Players and NPCs alike, something more to contend with and to help them out at the same time for those who can read astral sigs.

Of course what you may consider a active or passivability may differ, but it your game, do what you think is best.

What you're talking about is more an Astral Impression than an Astral Signature. Astral Impressions could belong to anyone, as theres very little in the way of identifying marks. Astral Signatures are like finger prints left behind from a certain style of magic and the exact way they alter the mana in a conscious, rather than unconscious, way.

What about if you're "actively" using 1 force point or more of powers at a time then it leaves a sig otherwise it's just under the curve of noticeability.
I also believe the power are subconsciously activated so unless, for example, you make a perception test the enhanced perception power is not "on".