If your Army Faction is GREY KNIGHTS, at the end of your opponent’s turn, you can select a number of GREY KNIGHTS units from your army with this ability (excluding units that are within Engagement Range of one or more enemy units). The maximum number of units you can select depends on the battle size, as follows:

Combat Patrol - Up to 1 unit
Incursion - Up to 2 units
Strike Force - Up to 3 units
Onslaught - Up to 4 units

Once you have made your selections, remove those units from the battlefield. In the Reinforcements step of your next Movement phase, set each of those units up anywhere on the battlefield that is more than 9" horizontally away from all enemy models. Any units that are not on the battlefield at the end of the battle count as destroyed.