Sticking together didn't help much first time round. Formations ended up too close and intermingled and so engaging something on its extreme flank broke two formations. So one thing I learned there was the 5cm intermingling is a very important distance.
So, I want infantry in the middle, chimeras as a ring/semicircle on the outside (to give saves to the formation if out of cover). A supporting formation >5cm away (to avoid intermingling) but with many models <15cm away to get supporting fire if engaged. I want some scouts 15.1cm away (10cm control zone for scouts, 5cm for inf/mech/etc., 0.1-0.4cm gap is too small for any models base to fit into, I think min base size is 5mm on one front?) creating a deadzone between them but also leaving the scouts outside of supporting fire range (to avoid the inevitable breaking of the scouts leading to blast markers on the formations that supported them). Get some AA for the formations.
Then hope they don't have much with BP

Or am I misunderstanding?
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Hey Matt! Thanks for the game. And the commentary throughout. I understand it was a lot of points committed to the engagements, but due to the sheer mobility of the forces you used there was little I could do to stop them grouping to make those assaults, the forces could condense and disperse rapidly, so while it was 1400 odd points, it was 1400 odd points that could have attacked from anywhere. Is that why I need more AA?
Considering what was on the board, how could I have deployed or moved to make those high point assaults a greater risk on your end? I feel fairly certain I'd come out on top in a straight up gunfight - volume if nothing else - so I need to find some way of making the risk of the assaults higher to discourage them.