Long story short, I'm playing a Biomancer psyker. Since about the second session of Dark Heresy my group's known that I was planning to pick up Regeneration. My Psyker's approaching Rank 6, and I figured I'd finally get around to picking it up. However, my GM finally took a good long look at it for the first time, and I think he very nearly fell out of his chair, before quickly going on a rant about how insanely overpowered it is (granted he rants about close to everything in Dark Heresy, Psykers just seem to be his preferred target).
Needless to say he's less than thrilled with the idea of my Psyker obtaining the ability.
Recently I've been discussing with him methods of balancing out Regeneration via Houserules. Thus far I think the only idea we've agreed on, is to give it some semblance of the Healer power drawback, in which there are severe consequences for attempting to use Regeneration multiple times within a certain timeframe (what these consequences are, and what that timeframe is, is still on the discussion table).
One idea he has proposed is to change the power almost entirely to: "Recover 1d5+WPB in damage, and, if this would bring the caster above his starting wounds, he may regenerate one lost limb, organ, or recover permanent characteristic damage" with the stipulation that the Psyker in question must have LOST a limb, organ, or suffered characteristic damage to use Regeneration at all.
While certainly a more acceptable version the power, the issue I take with that particular example is that it's rather underwhelming for a Power with a Threshold of 23. Regrowing limbs, granted, is exceptionally powerful, but even so, if comparing it to powers like Soul Killer or Telekinetic Barrage, it just no longer seems to hold up.
So I suppose I'm looking for suggestions as to how to balance out Regeneration, and make it acceptable for a Threshold 23 power, without "making the Psyker completely unkillable, unless you're using Flame weapons."