If you could make a formation with in reason that is what would it be?

[Xaric]

Knight Company

Knight Paladin or Errent
2X Armored Sentinel Squad
1X Scout Sentinel Squad

Man at Arms
A Sentinel within 4" of the Knight Paladin the Knight may choose to re-roll his failed invaluable save at the cost of 1 sentinel and the sentinel must take vehicle exploded results on the table.(due to the overload and discharge of power)

Protecting Gaze
The Knight may redirect his Shield to protect 1 Squad of Sentinel with a +3 Invulnerable save this meens he cant use his directional shield for that turn on him self.

[Pssyche]

I'd be happy just to get updated versions of the Eldar Formations from First Edition Apocalypse.
Particularly the War Walker, Seer Council and Hornet Formations.

[Morgrim]

I want some sort of nice Kroot mercenary formation that I can take with armies that aren't Tau. Mostly for fluff reasons. (I want to pair them with my Dark Eldar. I know this is a very poor combination on the tabletop, but I like Kroot yet severely dislike Tau and this makes me sad.)

[Mr Mystery]

Freebooterz Flashgitz.

GIMME MOAR DAKKAS!

[John Bower]

Imperial Guard Combined Arms Regiment:

1 Regimental Command Squad (must take Regimental standard)
3 + Infantry Companies (Each must contain 3+ Platoons)
1 or more Tank Companies
0-1 Artillery Companies (any type and units may be mixed (ie 1 squadron of Manticores, 1 of basilisks and 1 of Hydras) etc.

Fearless, all units in the formation have the fearless USR. The Regimental Standard counts as 2 wounds for determining Close Combat Results.

[This Dave]

Deathwatch Kill Team. Sternguard and/or Vanguard veterans all. Maybe allow them to take Preferred Enemy as they've prepared for whatever they're fighting.

[Calgar33]

You're in luck This Dave, that formation is in the Damnos Warzone book.

[This Dave]

You're in luck This Dave, that formation is in the Damnos Warzone book.

Yeah but the special rule they get there is just they get special ammo to use against Necrons. Cool and all but kind of limiting when they're supposed to fight all kinds of xenos.

[Blood Shadow]

Deathwatch Kill Team. Sternguard and/or Vanguard veterans all. Maybe allow them to take Preferred Enemy as they've prepared for whatever they're fighting.

This

[Calgar33]

This Dave, the second rule gives them Preferred Enemy against one Codex of your choice. The third rule even gives you extra VP.