It is possible to gain up to additional +20% ranged critical chance with maxed out Rock Mastery tree and Aim combination exploit. After area transfer, Rock Mastery's ranged critical chance bonus is applied over itself, but only as long as the archer stays strictly within Shale's aura limits (which makes this minor bug tolerable and definitely not game-breaking). Turning Aim off, then on, will net you a further crit chance boost, as Aim will now take the Rock Mastery bonus, that was wrongly applied twice, into account. This minor exploit is successfully used here to attain 77.20% critical chance due to Aim + duplicate Rock Mastery combo: http://www.youtube.com/watch?v=iFkR2qF7zs0
Permanent auto-crit for the whole party is attained with this exploit's help here
Aim speed and missile deflection bonuses are doubled after area transfer as well.
pc As of patch 1.04, Haste and Swift Salve decrease aim speed rather than increasing it. Rock Mastery, effectively overriding any negative speed modifiers, can be used as a workaround. See Bugs (Origins) for details.
ps3xbox360 This aura adds 7 seconds to ranged attack animation time rather than decreasing it. (The bonus to ranged attack speed functions normally on the PC version of the game.)