In your Shooting phase, when a friendly Adeptus Astartes Transport unit has shot, you can select one enemy unit hit by those attacks. That enemy unit is assailed until the end of the turn:
Captain model only. In your Movement phase, if this unit is embarked within a Transport unit, you can select one friendly Adeptus Astartes Infantry unit within 6" of that Transport unit and select one combat doctrine. That combat doctrine is active for that Infantry unit.
Adeptus Astartes Infantry model only. If this unit disembarked this turn:
One friendly Adeptus Astartes Transport unit that has an Adeptus Astartes Battleline unit embarked within it.
End of your Movement phase.
Select one objective your unit is controlling. That objective is secured.
That Adeptus Astartes unit.
Any phase, when a friendly Adeptus Astartes unit embarked within a Transport is selected to move.
While making that move, each model in your unit can be set up within the set-up distance of that Transport. This allows you to set up your unit within the set-up distance of your Transport, instead of wholly within that distance.
One friendly unengaged Adeptus Astartes Infantry unit that was eligible to fight this phase, is wholly within 6" of a friendly Transport unit, and is eligible to embark within that Transport unit.
End of the Fight phase.
Your unit embarks within that Transport unit.
