UPDATED: I ran some more tests, and there is NO visual animation when this effect triggers (or if there is, it's subtle, and gets lost in the noise when focused accuracy enables) The effect is (briefly) described as 'Boost Up' in the Combat Attributes monitor, and it seems to give a +40% to hit bonus, and +80% to damage (at lvl 50) -- but the ffect does not last very long - it *seems* to be even shorter than the 10s of real build up, but I wasn't able to time it accurately.
So: the proc 'works' - and the bonuses are substantial, but the only place I can see this being useful is if you slotted it into your 'build-up' power to occasionally get a super-build-up. If you slot it into a toggle, I don't think you'll ever get any benefit from it, because it seems to activate when the toggle is first enabled. At least, people are already used to rushing their attacks after clicking build-up...
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So, have you guys actually *seen* the Build Up effect happen, ever?
I have Gaussian: Chance for Build up slotted into 'focused accuracy', and have been toggling the power on and off for about 10 minutes non-stop (I know, I have too much free time!) and I have never seen the build up effect happen. (I'm also monitoring the damage bonus combat attribute directly, in case there's no animation, but I don't see the damage bonus change, either - when I use 'real' build-up, I see the value move.) Previously, I had G:CfB slotted into invincibility, but I never saw it do anything there, so I moved it to FA, because I leave INV up pretty much perma, and I thought maybe the proc only took effect when the power was activated. Now I'm not sure the enhancement even does anything!
Does anybody know *when* the proc roll happens if you slot this into a toggle? I would have thought it would happen at startup, but I don't see it. Does it have to be slotted into a click power? The only click power i have that would take it is.. build-up! (which might be cool, to occasionally get a mega-build-up, but...)
Any ideas?