I like the Rogue Trader psychic system because the Psy Rating (PR) used to focus a power doesn’t affect the chance of psychic phenomena and PR, not WP, is more important in determining the effects of a power. I like the Dark Heresy system because the more powerful powers are harder to use (not just costing more XP to learn) while the weaker powers can be easily used (provided the psyker is powerful enough). So basically this set of house rules is my attempt to bash together the parts of the two systems I like.

Instead of rolling (up to PR dice + WP bonus) for focusing rolls change the focus roll to:

WP bonus + modified PR + dice

dice (and PR) is determined by whether the psyker is using the power fettered, unfettered or pushing.

If the total of the roll equals or exceeds the power threshold it is successfully used. Overbleed is removed.

Unnatural willpower does not multiply WP bonus instead add the multiplier to PR (like in Rogue Trader)

Successful use of invocation boosts maximum fettered PR by 1 (like in Rogue Trader)

Fettered

PR is halved for all purposes. Roll 2d10 take the highest. No phenomena.

Unfettered

use full PR. Roll 2d10. Rolling any doubles results in phenomena.

Push

Add 1-3 to full PR (1- 4 if unsanctioned). Roll is 3d10 take the two highest. Phenomena automatic with +5 to phenomena roll per boosted PR (+10 per PR boost if unsanctioned).

Power well is changed to adding +1 to focus rolls when unfettered or pushing.

Discipline focus only adds a +1 to focus rolls when focusing powers of the appropriate discipline. (probably going to drop this talent)

Discipline Mastery works like in Rogue Trader (add 1 to your fettered PR)

Obviously the Dark Heresy powers will need to be modified to use PR instead of WP bonus for determining their effects (like the damage dealt by bio-lightning) and will probably need to have some more adjustments due to the removal of overbleed. I’ll probably be using the Rogue Trader version of powers if their is overlap and as a baseline for re-writes.

Also the thresholds would need to be adjusted upwards a bit (especially for the minor powers). At the moment I’m going to go with powers with a threshold <10 go up 3, powers with a threshold 10-14 go up 2, and thresholds of 15+ go up 1.

Thoughts? opinions? Obvious pitfalls I’m missing?

There are a number of posts on this particular subject... Including ones I made myself. Gonna say now, this is a can of worms subject, and everyone house rules this I think to suit their games.

I tend to agree with you, in that ALL occurrance of WP should be swapped out with PR.... Which they did in Death watch and I am very happy with.

secondly favored of the warp needs to be removed...if they want to avoid perils, then fetter. THE END.

Doing this solves 100% of the psyker cheese in my opinion... Yes, they can still be broken, and yes they pay the price.

Pretty much an excellent fix in my opinion.