sturmrider

Valid point, altho it doesn't impact the legality.  
 
Attacker makes the attack against a target.  If the attack hits the target, at his full DCV:
--target becomes the centerpoint for the AoE, until the END pool empties. 
--Target and anyone else in the AoE are Flashed. 
--Anyone moving into the AoE, either by their choice OR due to the target moving, is Flashed.
--The duration of the Flash effect is separate from the duration of the Flash power.  Once hit by the power, the Flash effect duration (which is in segments) applies.  If the Flash power's duration (which is in phases) extends beyond the effect duration, determined on a person-by-person basis since different people may be affected on different segments, then the Flash power takes effect on them again.  The key point is to recognize that the two timed effects are separate.
 
If the attack misses, or when the power's targeted at a hex...the point of impact has to be determined.  That's case-specific, clearly.  But once that's determined, that is the centerpoint for the AoE, and the rest follows.   
 

How do you handle an AoE Darkness field say of 8 meters that is placed on an opponent. Does he instantly know the shortest way out and walk out or if not does he walk in a straight line till he is out of it. Finally does he grope around moving randomly till he finds his way out. I found nothing in the rules on this and it is great his DCV is 0, but if he moves in the next phase you may not get the chance to take advantage of this.

Hey Larry!
Sorry for the delay in responding — the latter part of February was unusually busy, and then food poisoning/a stomach bug sidelined me all last week. I’m only now catching up with things.
 
I’m not sure I’ve ever written about this; if I did it was years ago, for one or two editions ago, and I have no idea what I said. So, I reserve the right to change my answer if someone finds the text you think you remember. (I thought it might be on 6E2 7-14, but I didn’t see anything there.)
 
If a character applies Invisible Power Effects (Sight Group; +½) to Darkness for Sight Group (or any other combination of the same Sense(s) Group(s), or other Sense-Affecting Powers), how you describe it depends on the special effects involved first and foremost. The game effect is that there’s a “blank zone” in the character’s Sight with no obvious cause. He just can’t see anything there — not the Darkness (which the Advantage makes invisible), and not the underlying area (which the Darkness hides).
 
The bizarre “logic” of this is a good indication that the GM probably shouldn’t allow this power unless the player has a reeeeallly good reason for it.