Astra Militarum suffers from having the absolute least mobility of any army in the game.
That's what makes them so utterly difficult to win with. If you move, you lose out on firepower if you're in a vehicle, or you get blasted to pieces if you're infantry in the open... and then your heavies are pooched.
Chimera are expensive, if you're using them as taxis. 70 points with a Dozer Blade, instead of 40 points for a Rhino with Dozer Blade. Both let you fire a pair of upgraded weapons from the top, but one costs a lot less and loses next to no firepower for moving 12".
This codex lost nearly all available means to gain pseudo-mobility, such as reliable outflank ability [Yay, Scout Sentinels!], infiltration [Ratlings, Yay!], and deep strike [Scions... Mediocre!].
The fix is to bring that back.
Harker should give out h-j's for his points cost, along with infiltrate, but that's not there. At the very least, a Dutch Rudder. Captain Al won me nearly every game of 6th edition that I played, where are you!? Vendetta, why can't you transport a full squad? I play tested you, you're the right points if I could drop a Vet squad out of you!
Failing that, I've been using Guard as allies to my Blood Angels, and dropping 3 pods with Melta CCS, Melta Vets, and Plasma Vets on the first turn. I sling orders around like nobody's business and it's awesome.
No plodding along for 3 turns trying to get somewhere. I'm there 1st turn, kicking nuts in a transport that's half the cost... and I never need to worry about my ride getting blown up before I get there.
Give Guardsmen access to a Drop Pod equivalent, and pretty much every worry goes away. Let two Sentinels ride a single pod. Give them transport capacity of 12, since G's are smaller than SM. It would basically kill off Scions, but who plays them anyway? [
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To be honest, I'm not using Ratty's because they're not useful in my metagame. They could be 8 points each, and I still wouldn't use them, and while an even MORE improved cover save may be valid, a flamer / cc squad is still gonna roast / spit them.
Squad size isn't keeping me from using Sentinels. Overly expensive flyers are doing that, I just don't have the points. And since a Valk has no meaningful anti-air to protect the squad inside, I need something else to do that, so I buy a Vendetta and stick a cheap token unit inside to drop on an objective. 500+ points later... I don't need 5 Sentinels, I need more points.
Old timers already have LRBT's and Demolishers. I know, I had 2 before the new kit came out. If they were reasonably pointed, why would those old timers buy new tank kits? Make them expensive, so they go and buy some Exterminators and Eradicators.
I agree the LRBT and Demo should be cheaper.
Hydra suffers from not being a Wyvern, when it gets down to it. What? The new kit is super-duper-mega-killy? [Yes, I've changed my stance on them, as I've moved away from platoons.] You'd have to make a Hydra pretty damned amazing to compete, kit wise, with a Wyvern, much less to make it compete on the tabletop. Hmmm, which one will I build?
Mostly, it needs AV 12 on the sides, and to pitch open topped. It just needs to be a little bit more durable. Getting rid of Skyfire's snap-shotting non-airbourne units would go a long way.
Standards should give +1 Ld to units within 6". Company Standards should do that, plus what they already do. I mean, is the +1 combat res supposed to be a joke? 'Cause I laugh everytime any one of the PCS members survives a round of combat.