T4: Set aside formations in reserve

You can keep certain types of formations in reserve, so that they are not deployed on the table at the start of the game:

Aircraft formations, and formations that will enter play aboard transport aircraft.
Formations that will enter play via the Planetfall or Self-Planetfall abilities.
Formations in which all units have the Teleport ability.
Other formations where special rules clearly mean that they can be held in reserve, as with formations that will use an Eldar Webway Portal for example.

These formations are not secret and your opponent may inspect them at any time.

Units that are being transported must start the game already embarked on the transport vehicles that will bring them into play (that is, embarked on transport aircraft, transport war engines, or units with the Planetfall or Self-Planetfall abilities).

Formations that are in reserve may not carry out any game functions or use special abilities they may have (apart from those that are essential for them to actually enter play of course, like Teleport, Planetfall and Self-Planetfall!).Not quite complete. Somewhere there is a statement about how certain other special abilities may be used on the unit's own formation where it affects rallying or Initiative test, such as Supreme Commander.

FAQ

Q. When do I decide how formations in reserve will enter play?

A. Declare the means by which a formation will enter play at the same time that you set it aside and declare it to be in reserve.

Q. As well as aircraft and formations that will enter play via transport aircraft or the Teleport ability, can I keep any other formations in reserve?

A. Yes, but only where the rules make it clear that the formation can or must enter play via some other special ability or circumstance (such as the Tunneller or Self-Planetfall abilities, or being embarked on a surface-based war engine), or where the scenario makes this clear (as with some of the training scenarios).

Q. Can I activate a formation that is in reserve?

A. Yes of course, or else how will you get it into play? To be clear, while formations are in reserve you do not have to activate them — but when you do, you must use the activation to get the formation into play.

Q. Are there any limits as to what actions I can choose with a formation that is in reserve?

A. Yes, you must choose an action that will allow the formation to enter play. Sometimes you may be limited to a particular action. For example, when you want to bring an Eldar formation into play through a Webway Portal, and that portal is inside an enemy unit’s zone of control at the time, then you must choose an Engage action.

Q. What happens when I fail the Action test for a formation in reserve?

A. Like any other failed Action test, your formation gains a Blast marker and must take a Hold action. Then, you must use this to move the formation into play. In the rare event that something would prevent this move into play (as with the Eldar Webway Portal example above) then leave the formation in reserve, with the Blast marker — the rest of your activation is wasted, better luck next time!

Q. Normally, we must activate all formations during the action phase. What about formations in reserve?

A. You don't have to activate formations in reserve. But, when it is your turn to activate a formation, you may only choose not to if you have no more unactivated formations in play on the table and you do not intend to bring any more formations into play from reserve this turn.

Q. Can I choose to activate a formation in reserve when I have no way to bring it into play (for example, Necrons in reserve with no portal left to use), so that I can effectively 'pass' the turn for activation back to my opponent?

A. No.