Variable sizes are fine. Some formations are effectively alternate FOC's with different rules instead of ObSec. The Flesh Tearers Strike Force is effectively a CAD, less a couple Troop Choices, plus 3 FA slots. And you have one min HQ, Troop, and FA. You get Rage on a certain charge roll or better, instead of ObSec.
That's pretty cool (I think...I don't know Marines so good).
Wait, that's it! The infantry company! I could leave it up to the player to decide what to put into it! Think about it...an infantry company might be a fresh, newly raised one full of rookies, or one that's been in operation for years and is full of grizzled vets!
So with that being said...how about 1 Company Command Squad, 1 Commissar (must join one of the units), and 3 Troop choices. So that's either platoons or Vets! With an Astra Militarum warlord trait re-roll, Directed Firestorm and Supporting Fire? Is that more workable?
The Rules look ok. Maybe an option to take a Lord Commie. That way, his Ld Bubble could boost multiple squads, which would be quite useful for MSU. Further, as a unified group, you could add a rule that they roll for reserves as one unit, if they're in reserves.
Did you try making this Scion formation, plus a CAD? How many points go into 20 Scions with Guns and Stuff? Plus a Commie? How many points did you have left to build the rest of the army with? 500+ points of Scions is a tough swallow for most lists, so maybe you could create a sample list to see it in the light of?
This is were it gets a little disheartening. A CAD of 1 CCS, 1 Platoon and 1 Vet squad all bare bones came to 250pts. Then the Scion Formation, bare bones, came to 320pts. So that's 570pts just to get the models needed for it. Realistically, with all the necessary upgrades, it's going to come to well over 1000pts. Check out this list (using many of our changes) for example:
CCS
Commander with Kurov's Aquila, 4 vets (1 CCS, 1 Vox Caster, 1 lascannon, all with camo gear), MoO, Ootf, Astro (243pts)
Infantry Platoon:
PCS
Commnder, 4 guardsmen with 2 plasma guns and autocannon (70pts)
Infantry Squad
Sgt with boltgun, vox caster, 2 plasma guns (86pts)*
Heavy Weapon Squad
3 autocannons (75pts)*
* Combined
Infantry Squad
Sgt with boltgun, vox caster, 2 plasma guns (86pts)**
Heavy Weapon Squad
3 autocannons (75pts)**
** Combined
Veteran Squad
2 melta guns, 1 flamer
Chimera with multilaser, heavy flamer (150pts)
There's 785pts spent on a not too special CAD.
Now for the Scion Assault Force:
Commissar with power sword: 40pts
Scion command squad
Prime with power sword, platoon standard, vox caster, 2 melta guns: 135pts
Scion squad
5 scions, vox caster, 2 flamers: 85pts
Scion squad
5 scions, vox caster, 2 flamers: 85pts
5 scions, Scion squad, 2 flamers: 85pts
So that's 430pts for a basic 20 man, 3 squad assault force. Altogether, the army is 1215pts. What do you guys think?