I'm currently planning a game, and one of the intermediate enemies will be, if possible, a woman with Psychic powers allowing her to vanish.

Does anyone have any good rules for invisible enemies? I'm currently thinking of giving players a -30 per test to identify which square of the combat map she's in, and a -20 or 30 to the BS test to hit her. Other methods of ascertaining what square she's in will be available will be luring her into nearby water, psyniscience (1dos identifies square, 2 removes penalty to BS test), or basically whatever clever method they think of- these negate the perception test but not the BS penalty.

Is that any good?

Those look pretty good to me.

An alternative would be to treat them exactly as if anyone who attempted to attack them were suffering from blindness, or complete darkness. I believe under this situation BS tests automatically fail, and WS tests suffer the -20 or -30 (can't remember and the books are back home)

I remember that the power Distort Vision requires a hefty psy check to ascertain the correct location of the psyker, so using this as an additional method of locating them.

Anyone with Heightened Senses (Hearing) can utilize the benefits, and Heightened Senses (Smell) if she's got a noticable odor.

Will you grant a bonus to detecting her if she's bleeding? I'd imagine that blood which has dripped to the floor around her will become visible once it has left her immediate person.

I use some kind of mix between the psychic power "Chameleon" (Core p.165) and the "Chameleonic Scale" trait of the Lictor in the Creatures Anathema (p.94). I give +30 to concealment or -30 to awareness (I still don't really see the difference in the end so choose whichever you want) and -20 on WS and BS in battle. There is a lot of things you can change depending on the situation or the nature of the invisibility, but I use that as a simple way to deal with this.

IdOfEntity said:

Possibly. The environment is gantries over the sea, so a blood trail may not be terribly visible. I do like the gameplay implications though-as in, success breeds success.

(Ooh, I could just draw it on the map (this is a pbp game) and let the players figure it out)

Thanks for the idea. Will reserve it for if she starts beating them.