I'll probably be giving this a try. I can already spot several grammar and syntax mistakes. If I do get around to playing this I will be sure to point out any mistakes I find. Looks fun enough from what I can see.
I would suggest you use another method to make your hero shoot other units. Perhaps make it when your hero is ordered to "smart" an enemy unit (right clicked). That way you still have the same clicking gameplay but your hero is never deselected. Note that you might have to order your hero to...
I'm sorry, I just realised I was offering bad advice. (Talking about the For Loop bit, totally meant Pick Every Unit). Anyway here's what the working version would look like: (you were close)
Flurry
Events
Unit - A unit Starts the effect of an ability
Conditions...
Well it shouldn't be that hard to modify your trigger to work as intended. Just add on a For each Integer A from 1 to number of units in FlurriedGroup then move the dummy creation part into that loop and you're done.
You already did the "hard" part.
EDIT in response to your edit: Same...
Storm Bolt has a hardcoded casting time that's not instantaneous. Basicly the dummy can't be casting its ability more then once per a certain duration.
If you want to use Storm Bolt over Warstomp you will need to create a dummy unit for each unit you want to stun.
EDIT: Looking over your...
They are, but that was modified through a trigger. It was converted to use neutrals to allow 2 observers for tournament monitoring. The 6v6 map you see popping up is just a modiffied version where the 2 free player slots are added on. I assume those players are the real red and green...
Actually both versions of DotA use neutral creeps for the bases. That's why they don't show up in the game lobby. Neutral units have weird issues and tend to ignore buildings.
I assume you're using a fixed random seed. If you try testing your map without executing it from world editor does it still always move to the same position?
Edit: so close...
I'm fairly certain there's a follow through time hard coded into Storm Bolt that would account for the delay. If you want it to cast seemlessly you will need to create a dummy unit every interval and order them to cast individually.