"If several Minifigs are in position to attack the same target, they may all combine their attacks together, adding all their Damage into a single massive roll."
I used this to great advantage in my first battle. However I wonder if I was doing it right? It seemed way too easy to gang up and kick the snot out of my son's army one by one.
All I did was keep my melee units bunched up, move in on one of his guys, and during my Attack Phase I declared all of them were attacking the single opponent. Sometimes it was 4 on 1 and he stood no chance. The worst assault was when I used 4 melee and 2 ranged minifigs to obliterate his hero during one attack phase.
Did the same with ranged minifigs. I didn't have nearly as many on the field as melee guys however I'd use the same tactic. Just kept them pretty close together, within 10" of his guys, and declare they all were attacking a single opponent. Usually resulted in their destruction.
