Just a hypothetical, not something I've come across but one of the other answers in this sub-forum made me think of it:

I have Flurry:
a) I successfully make the first attack and my opponent has Mystics, do I take the damage after the first successful attack, or do I wait until the whole power action is complete?
b) If I take the damage before the second attack and I lose Flurry, do I still get to make the second attack? (My guess is yes since I've already started the action.)
c) If I take the damage before the second attack, do I use the new values or the old values? (My guess is the old values, again, since I've already started the action.)
d) If I take the damage before the second attack and that damage KO's my character, what happens?
e) I successfully make the first attack and my opponent takes damage, do I use their new values or old values?

A) You take the damage after the first successful attack.

B) Yes you still get to make the second attack.

C) You use your new values for the second attack.

D) Then you are KO'd and the action ends.

E) You would use their new values.

You take it prior to the second attack, but not after the first one.
Seriously, the damage from Mystics is applied when the character takes damage. In other words, you take it DURING the first attack.
You do indeed. (This was not always true.)
You would use your new values. At the time of the second attack, those previous values don't exist. You can only use what is on the dial. In other words, while you may have a fully functioning memory, the game does not (usually...*shakes fist at Deathstroke*.
Total protonic reversal.

Actually, the action just ends. Play proceeds.
You use their new values (and powers, like if Toughness or Combat Reflexes appears).