Played against Tyranids the other day and our high I got in the way.
Lets see if I can recall it the situation.
My beast unit charged a group of harpies in a narrow corridor (between 2 buildings) and only 3 of my models could stand there at a time. My Khys was in the front with I6 and attacked first killing 7 harpies, we removed the models and then it was time for my Flocks to attack with I5 but I couldnt get close enough to attack any of his models. There was more than 3 inches cross my 2 rows of Khys, so they had to stay behind them and couldnt attack, same goes with the beastmasters, no luck with them.
Then it was his turn at I at 3 or something, he then moved up to my Khys and attacked them, killing 3 I believe.
My question is, was this done correctly? I could have wiped the unit in the first turn of combat if all my units could fight. Got his unit in the third round of combat.
Now that I think about it another question comes to mind. What if my flocks was in the front in 2 rows, blocking the Khys, would their attacks be wasted at I6?
Still have serious problems winning with DE and almost every game my opponent get first blood against me, with AV10 2HP vehicles, it kinda easy for them. Try to hide them but homing missiles, artilleri etc just seem to ruin my day everytime. We also play with some restrictions for all armies, making it very hard for DE.