Topic: clarification on formations

[Enigma the Black Dragon]

Hi guys!

Could someone explain a bit how formations work? I've never played them before but with the new harlie codex I'm inclined to try some of them.
I've read and reread the rules a couple of times but I still don't quite get it.
If I build an army of the bare minimum required in the harlie 'dex and then want to add a formation of harlies.
Do I:

• ...use the models I've already picked for the army and simply say that these three units are organized in a formation. Thereby keeping within the FoC
  

or

• ...add another unit of Troops, fast and heavy to fill out this new formation. Thereby taking more than the FoC allows

I know that formations are a kind of detachment, so I'm guessing at the second option, but It'd be nice if someone could clarify. I'm still trying to learn 7th. Hasn't got too much time on my hands now a days 

Also, does anyone have any tips or such for using formations? Anything a beginner should be wary of?
Cheers mates!

Removed differences in Force Organization between the two listed in the codex. --- GML

[Caercuillen]

You can build your army according to the FOC presented in the Harlequin book and/or use the formations presented. Either way you will be required to have models representing the FOC and Formation, but you are not required to take the FOC to use the formations you can just use the formations presented in the book.

I hope that answers your question.

[Ambience 327]

Formations are just another type of Detachment. You will need enough models (and points) to field both the Detachment and the Formation you are taking. Note that, barring restrictions placed by Tournament Organizers or agreed upon by players, you can field an army of ONLY Formations, with no Combined Arms Detachments, Allied Detachments, Masque Detachments, etc.

[Enigma the Black Dragon]

Thanks! Between the two of you the formation rules seems a fair bit clearer now.
One more thing though: Can I play a Battle forged army of Craftworld Eldar and then add a formation from the Harlequin codex? Or do I need to use the allied detachment for that?

[Lord of Winter and War]

The only stipulation in a battle forged army, is that the army must be made up of detachments. All formations are detachments, codex's have their own and there is the allies and Combined arms detachment in the rulebook.

You can take units from any codex as long as they fit into detachments. As long as you follow the extra rules based on who allies with who, you're fine to do what you want. I could take my Imperial Knight with a Tyranid army and include a formation from the Harlequins codex if I'd like, but then I would need to watch out where I deploy based on restrictions from "Come the Apocalypse".

The only benefit that allied detachment gives, is that you only need one troop and you still have objective secured.

[Ambience 327]

Don't confuse the Allies Matrix and the idea of Allies with the Allied Detachment. They aren't the same thing.

Any two Detachments or Formations from different Factions are technically "Allies". The Allies Matrix tells you how the interact on the tabletop.

As Killersquid mentioned, the Allied Detachment is just a way of adding some Allies to your army with less requirements than the Combined Arms Detachment or some other formations. It's benefits, restrictions, etc are listed in its rules.

[Enigma the Black Dragon]

Don't confuse the Allies Matrix and the idea of Allies with the Allied Detachment. They aren't the same thing.

Thanks! I must confess I've done exactly what I shouldn't then =)

[Ambience 327]

Don't feel too bad - it seems to be a very common mistake and I think it is at least partly GW's fault for using the same term for different things.