According to the description of the skill Psyniscience it should be possible to use it to detect nearby psykers, right?

Should a higher psy rating of a target make it easier to detect it or do mighty psykers also have means to somehow shield their psychic presence?

In the concrete situation I'm thinking about a psyker with psy rating 7 is posing as a lowly servant in a huge crowd at a Nobel's ball. There are also some other Astropaths present. Should it be easy for the Astropaths to detect the presence of the mighty psyker?

How would you handle this?

Your discretion.

I'd say that a more powerful psyker, much like a Daemon, would be a much more powerful blip - But that being said... Psykers with Strong Minded and Mental Fortress, much like a Daemon of Tzeentch, may counteract this bonus or even be harder to detect...

It's up to your discretion entirely. How difficult do you want it to be?

Doesn't psyniscience have a list of modifiers to the test like any other skill?

It does, just taking a glancing look.

I'd give a -10 to finding a psyker of any level in a group of humans (a turn on the normal modifier of a demon in a group of psykers)

Astropaths might be able to see the psyker regardless of psynicience depending on the traits and talents they took from the Astropath career in the Enemies Beyond expansion (or maybe it was Enemies within)

My understanding is that detecting the innate presence of other psykers is rather tricky and that psyniscience is most useful in pinpointing warp incursions or warp powers. If a psyker is not actively using their powers, I'd be inclined to impose a penalty or bonus for the psyniscience test depending on the PR of the hidden psyker, eg:

1-3 = -20

4-6 = -10

7-9 = +0

10+ = +10

If a psyker is using their powers with abandon, just use the appropriate modifier listed for psyniscience. Astropaths might give some other bonuses from their own psychic traits and abilities but I can't remember anything in particular.

Thanks for all the replies! I especially like the idea to take Strong Minded and Mental Fortress into account. I have to look at the Astropath powers in detail. What possibilities of masking their presence do daemons of Tzeentch have and where can I find more about that?

It seems to me you all agree that in principal a higher psy rating should be easier to detect, correct?

It seems to me you all agree that in principal a higher psy rating should be easier to detect, correct?

I don't.

I do, but only if it's detectable at all. I can easily swing both ways to it being detectable or not being so, but if it were to be, I'd see a higher PR being more easily found.

I allow players to use Psyniscience to detect psykers. Unless psyker is concealing his power in some way, I don't even give them penalties. For me, psykers of at least PR3 are easily detectable, if they are in range of Psyniscience. And I don't think that Mental Fortress or Strong Minded should give penalties to it - these are more of a psychcic defense talents, than hiding ones, but unfortunately, we do not have any official Talents thast I'm aware of that allow masking Psy Rating.

When I had such situation for the first time, I decided that psykers can try to hide their PR by making a WP Test as a Free Action, 'hiding' one PR per DoS (not cumulative, but they can of course try again if they fail to hide their whole PR). However, in order to 'unhide it' and be able to use it, they need to spend another Full Action and WP Test to restore it to full. If they hide all of their PR, they are undetectable by Psyniscience, save for some phenomenal success, like rolling 01 and getting 7 Degrees of Succes.

Aside from house rules, it's basically a GM's discretion. I see Deamons as being able to see psykers with their Improved Warp Sense no problem, that's why I ruled that Psykers are easily detectable with Psyniscience. But if you see it differently, you should make your own rules here.

And Daemons hiding... Deamon Princes of Tzeentch from Black Crusade have something like that, if I remember correctly; and I'd rule that Tzeentchian Daemons can hide their PR the same way as human psykers, but I don't see it possible to hide their demonic presence from psykers. Powerful Herald of Slaanesh can infiltrate upper echelons of Imperial Society, with her Daemonic Presence masking as sweet smell of something, weakening Willpower but not through fear, unless she wants to use it that way; but I'd say a Psyker will detect it quickly. That's why I see Astropaths as not only galactic walkie-talkie, but also a way to prevent Daemonic influence around Planetary Governors, Fleet Admirals and such.

At least that's how I roll .

actually i dont think you can detect a psyker with this skill. it says about warp entities and such. o psyker is not. at least a human psyker. i would allow a roll though if someone used a psychic power recently. i would consider the psy rating the power was cast and time since it manifested the power for any modifiers. maybe if someone was using warp perception from the divination tree could roll with psyniscience to detect another psyker.

Would you allow an Astropath who has Unnatural Senses because of the Sole Binding to role for Psyniscience to detect another human psyker? To me it somehow feels that the Unnatural Senses of an Astropath are something like a permanent Warp Perception.

are you refering to the unatural senses characteristic you gain from the astropath advance? well yeah you could rule it like the warp perception but i propose you limit this to human psykers since the astropath is soul bound to the emperor. so a player could detect a cultist psyker but not a deamonic entity that has psychic abilities. there are so many variations you can do. you can even rule that you need certain ammount of dos to detect someone or something. just try to be as specific as you can from the start and only rule differently if it really messes with your game(ex. you see that your players rely too much on a dice roll and it takes away the investigating felling the game offers)