I've had some discussions recently, and many more over a longer period, about how formations, detachments etc work and how you use them to create an army list, so consequently I figured I would write a post about how the whole thing works, as it can conveniently be filed amongst my army building articles. There are two elements to this, those who have played 40k before and those who are coming in fresh, so I'll try to differentiate where those different approaches are in the article.
So how do I go about choosing an army?
For those coming back to 40k - the 'force organisation chart' as it used to be known is dead. Buried. Deceased, it is pushing up the daisies - you get the point? It's now incorporated into the concept of the 'detachment'.
For everyone - there are 3 ways to select your army in the current edition of the game.
- Unbound - this is rarely accepted by most players and is by far the most uncommon method. This basically means you take whatever units you want and provided they don't exceed the agreed points level for the game, that forms your army. These can be from any faction, and there are no restrictions on how many of one type of unit you can take - you could bring an entire army consisting of nothing but thunderfire cannons, or all-gretchin, anything. The reason it's not very popular should be fairly obvious - the potential for game-breaking combinations and lists is quite frankly horrendous. I'm 99% certain GW really introduced this option so that no-one starting out in the game could grumble about the 'entry cost' of a minimum level army (not that it's usually that high for 40k, but the point remains. I'm effectively going to cease consideration of unbound lists at this point, because there are so many variables it gets ridiculous very quickly, and as I've already said, these types of lists generally don't get played much, and are rarely accepted.
- Formations (technically a formation is also a detachment, but for the purposes of this article you don't need to worry about that distinction) - there are many, many formations now in the 40k universe, ranging from simple little combinations of units to whole armies in their own right. Each formation brings with it certain benefits that only the units in the formation benefit from, and often contain certain restrictions. The key thing about formations is that they specify exactly what units you can/can't bring, even if sometimes there are optional slots or a choice of units. They are almost always quite restrictive and the command benefits usually relate directly to the type of tactics relevant to the units within the formation. You can build your army entirely based on formations, but another important thing to remember is that a unit can only ever be a part of a single formation (unless there is an explicitly stated exception). So if you bring two formations each requiring a tactical squad you must have two tactical squads in your army, one belonging to each formation.
- Detachments - similar in style to formations, these also bring their own command benefits and restrictions, however they are much more flexible in terms of the units that you can take, and are the most common exception to the 'a unit can only ever be part of a single detachment' rule. This is where the old style force organisation chart is reanimated, with the combination of the force organisation chart, restrictions and command benefits taking on the title of 'Combined Arms Detachment' or CAD. The CAD has morphed somewhat over the years and although you still require 1 HQ and 2 Troops choices, with the old maximums for each of the battlefield roles, it now also includes a fortification slot and a lord of war slot. This is important, because many of the newer nested detachments do not allow these choices, thus forcing you to use a CAD if you want either of those elements.
I want to talk a little further about detachments, as there has been a definite evolution in their use since 6th edition when the concept first materialised. Originally the detachments were similar in style to a CAD, for example the realspace raiders detachment in the Dark Eldar codex requires a minimum of 1 HQ and 2 Troops, but also a Fast Attack, and expanded the potential fast attack choices out to 6 rather than 3.
All this changed with the Necron codex, and the 'Decurion'. You'll probably hear of 'Decurion detachments' being referred to in the game, though I prefer the term 'Nested Detachment'.
These work in a similar way to the CAD, however instead of requiring 1 HQ and 2 Troops units, they require some combination of Core, Command and Auxiliary formations. You will need to be careful however that you meet all the requirements of the detachment as not all nested detachments have the same layout in terms of formations. Some only require 1+ core formations, others require 1+ core and 1+auxiliary formation per core formation etc, so read the codex carefully.
A nested detachment applies its own command benefits, similar to a formation, however these benefits apply to all units in all the formations that form the nested detachment. Units will still gain the benefits for the formation they are a part of in addition to the detachment benefits. A unit however cannot be part of two formations within the nested detachment.
Finally, it is important to remember that if you use a nested detachment to build the basis of your army, you can still take formations that are not available to a nested detachment whilst keeping your army 'bound (aka battle-forged)', they just don't get the command benefits of the ND applied to them.
My recent Iron Fists list is a perfect example of these methods of selecting an army, so I'll set out the philosophy here.
The Scarblade Strike Force is the name for the Nested Detachment, and it requires 1-2 Core Formations, 1+ Auxiliary Formations and 0-3 Command Formations
The Hunting Force is my Core Formation (a nested detachment always specifies which formations can be core, auxiliary and command elements).
I have then added 2 auxiliary formations in the form of a Stormbringer Squadron, and a Speartip Strike. I've exercised restraint by not including a Command formation.
Separate to the Scarblade Strike Force, I've then taken a Raptor Wing, which is a formation in its own right but cannot form part of the Scarblade Strike Force and therefore doesn't gain its command benefits. My army is still battle forged however because the Raptor Wing is a formation, and the models from it will gain the command benefits specific to the formation.
I think that pretty much covers things, but please feel free to ask any questions you may still have, I'll do my best to answer them.