I'm not sure if this has ever been discussed?

As a GM would you let a psyker tell his fellow group members that is about to trigger a power that will make him look very frightening and thus negate them having to roll a WP check and consult the fear table?

Or would you let the fellow members not roll because the psyker gave everyone fair warning?

I've heard of it played both ways and want to get a consensus.

I allow my Psyker to warn the players all he likes but still have the power effect them but allow them a small bonus to willpower for being prepared. I see the power as affecting all, not selective even if warned, after all a monster that you know will be scary is still scary when you see it. Plus in my games i try to assert the otherwhelming fear that psykers make among the common folk in dark heresy thus making them justifiably feared.

Thats what i do anyway hope it helps in some way.

Situation did not occure to me till now, no psyker with that power in game.

But here are my 2 cents:
First of all, regardless of warning, I would make the check for other pc somewhat easiere. One step lower on the difficulty, perhabs two.
My reason is, that the pc know that the psyker is on there side. He still might be frightening as hell, but some (or a lot) of the edge is taken away by the trust the pc have that he will not turn on them.

Imagine a roaring lion. If you are on the other side of the ironbars of the zoo, he is scary... but not half as scary as if you would be on HIS site of the iron bars!

Talking about warning... has the power any RAW that there has to be a line of sight in order to be effected? I do not know, but I would say so. If this is true, the pc can turn away. Otherwise...well... "aura" is "aura", after all. An "area of effect" would be needed to decide if the players are still effected or not.

It affects all but giving a warning gives a (in my oppinion) a +30 to the check, after all if he looks dangerous and demonic and you know he dont intend to harm you and have not turned demonhost, then its not that bad.

Thanks everyone that makes sense!

It hasn't come up in my game yet. But seeing as how in mine the other pc's view the psyker as a potential threat since she can do really bizarre things with her mind like force someone to shoot their colleague when he's not looking and has actually gotten one of them killed. I wouldn't give them a bonus to the roll. If anything I'd give a penalty because they know how bad she can get.

But if in your game the psyker was viewed as a comrade that they trusted then yes I'd give bonuses.

in our group the psyker has to tell us before he casts a power like that, otherwise we would put so many shots into him that he would resemble swiss cheese. Our current characters had quite a bad experience with the previous psyker that was with them, (suffice it to say that player liked rolling a lot of 9's, so any power use was fun).

The Psyker in my group has stumbled onto the particulary shady combo of kicking off Inspiring Aura then Fearful Aura to boost party resistance to Fear checks then bring on the scare.

Smart little ...grumble grumble...

Anyway yea warning sounds fine a small bonus I suppose if you feel nice

Has come up a couple times but no involving the whole party.......When it does i'd say that a bonusto the WP test could be argued for. Of course I thought that you had to see the psyker to be affected by the fearful aura.....I'll look back into it.

It all comes down to how you as a GM are feeling at that time.