To use a power a librarian just roles under his wp? un modifed unless he has a force staff? Is this right? as it means most libbys will fail to cast 50% of the time unless they start using fate for re rolls? it seems a bit harsh as in shooting and even at times in CC + modifiers seem pretty easy to get, or am i missing something?

It really depends on the power you use. When you do a Focus Power test, you also add 5x the PR used to cast the power. So if you have WP50 and cast a power at PR2, you need to roll 60 or under.

I've been using Smite alot lately, especially against Hordes, as this uses the same modifiers as shooting. So a WP50 guy firing smite at PR2 at a Magnitude 30 Horde should be rolling 50+10+30 = 90 or under (as 91-00 always fails).

Don't forget that the power level that you are using the ability at will modify your PR

I.E. If you have a PR of 3 with a Will Power of 50 and are casting Smite.

Fettered (PR/2 Rounding up): 50+ 10 = 60

Unfettered(PR): 50 + 15 = 65

Push(PR + 3): 50 + 30 = 80

ah that makes more sense and the libby more useful

Also remember the psy powers tend to follow your standard mage/spellcaster power curve, where you're middling to weak at the start, and then grow exponentially and in many cases outclassing your peers. And don't forget the libby starts with a force sword