The to-hit rolls are made at the beginning of the animation. This is most obvious with ranged attacks against a moving target: an attack that will hit will curve to follow the target, while an attack that will miss will go in a straight line. Damage and other effects are applied when the attack hits, though, so you can, for example, see a hold attack coming and pop a breakfree ahead of time.
Similarly, resistance powers can take effect during an animation. If you're being hit by a DoT and toggle on a resistance toggle, the remaining damage ticks will be decreased.
...I forgot what experience means.
So when exactly are accuracy and defense rolls made for an attack? At the very beginning of the animation, or at the moment of impact?
I was wondering because I was fighting BAB and he started winding up for KO Blow and I decided to pop a couple of purples in hopes to avoid the devastating impact. It seemed to work, but I didn't know if I got extremely lucky or if popping the purples actually helped.
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