So, Untouchables reduce the Psy Rating of a psyker by 5. How does this affect psychic powers that are being sustained? IE: If a power is sustained at a Psy Rating 8, does it go down to a 3?

The book says it lowers their Psy Rating, so I imagine this shouldn't do anything to a power that's already activated and being sustained.

Finkswitch said:

My view, the psyker is no longer able to channel a Psy 8 power so he would loose the sustained power.

If I was GM, I would be mean about it and force a WP test to avoid some form of phenomena at the loss of control.

I'd treat it like I'd do any other source of psychic reduction, from sustaining multiple powers or whatever else.

The effective psy rating of all sustained powers, and future cast powers, decrease by 5. So if he's sustaining a power at psy rating 8, it's now decreased to 3. If decreasing it causes it to get an effective psy rating of 0 or lower, it shuts down. If sustaining more than one power, this would increase the effective psy rating of all other powers by the appropriate amount, since less powers are being sustained.

Moving out of the sphere of the untouchable would remove the penalty, and all still active powers would be bumped up by 5. All deactivated powers, however, would remain deactivated and have to be cast again.

In the case of having multiple powers in risk, yet enough active that shutting down one would preserve another, either remove the one cast last or let the player choose which to lose.

@ItsUncertainWho

Technically, all psykers can always channel psychic powers of any strength at all times. With stuff like Boon of Tzeentch, a psyker could easily sustain a psy rating 10+ power at psy rating 5, yet he's still capable of sustaining a power of higher psy rating. Hell, just pushing is enough to get you to a effective psy rating higher than your actual psy rating!

Reverend mort said:

I just tend to be mean to psykers. The dirty, filthy creatures deserve no less.

I also think that the Null rules are sorely underdeveloped.