Hi,

when a psycher uses his power, does he have to make any gestures, noises, incantations, … Or can it be silent and unnotices? (execpt when the warp is unleashed)?

I've never heard of it being a requirement for them to chant, gesture, etc. Now, many of them would anyway, especially those from more feral or shamanic traditions, or those with a religious bent may chant or pray but that's more if they're using the Invocation talent. At any rate, these are psychic powers and thus simple concentration is enough. This is really important for some powers that are best when they are secret, like telepathic powers.

Generally psylers are depicted gesturing and sometimes with a crackle of energy around hand/head.

I reckon it depends on the amount of concentration required. Basically if a psyker is rolling all of the dice he/she possibly can then I reckon they are gesturing/incanting in order to help their concentration. If they are rolling half their dice or less they don't need to.

Obviously some powers themselves have obvious visual (and therefore probably audio etc.) effects and are therefore not subtle at all regardless of the level of concentration. Others (such as telepathy) probably could be cast quietly even if it is difficult. I would be tempted to put increase the difficulty of the power roll to do it.

Although this is mostly in Black Library fiction, but the use of psychic powers tend to cause an unnatural drop in the temperature. Depending on the power of the psyker and the magnitude of the psychic ability being used, this can range from a minor chill in the air to a major frosting of the surroundings.

As for gestures and incantations, that depends on the type of power being used by the psyker, although you also have to take into consideration his training and personal beliefs. Gestures and incantations help focus the psyker on the task at hand, but bear in mind that these are not only mere words and motions. Arcane words spoken aloud and glyphs drawn into air hold a symbolic meaning as well, reinforcing and supporting the flow of the warp energies through the psyker. Of course, if the psyker is strong enough, he may be able to bend the warp to his will without the help of these aids when it comes to simpler tasks, but greater undertakings will require greater effort. So, if you are summoning a Daemon Prince - let's not dwell on why you should be doing so -, an incantation and some gestures won't do the trick, you'll need a large amount of research, special candles, sacrifices, specifically written spells, perhaps some ritual fasting and whatever else that might seem necessary.

Totally not arguing, but I have never seen it that way, Seqvrin. I guess the art in the FFG books backs you up, but for whatever reason I always figured they were hamming it up and showing the most impressive powers. In the Black Library books, there are lots of instances of simple powers being almost undetectable. The most common "symptom" is the presence of psychic frost and whatnot, and that's usually when they're using a lot of power. I'm thinking of Ravenor a lot here. Like I was saying, I guess the gestures and chanting always seemed more tied to the use of the Invocation talent. I don't think I would ever play as making it harder to cast one without someone else's notice.

What do you guys all think? Do you play it as a subtle thing or totally obvious?

Magos Seqvirin said:

This even goes for pyromancy. I recall that one of the Librarian Novitiates in the Soul Drinkers nearly froze himself to death summoning a wall of fire hot enough to melt ceramite. Or something to that effect.

Sorcerors (as in those who have skill through knowledge and magic) have to make gestures and other things, there is no other way. Psykers are more free, but as it is innate, well a good chunk of it will them doing weird things as that is the way they do it.