When do you have to decide to use External Racks? Do you have to declare it at the beginning of the attack or can you decide whether to trigger it after your initial roll...like when you add a CF command extra die.

It happens in the "Resolve Attack Effects" stage of attack resolution. This is right after you roll attack dice.

3 hours ago, itzSteve said:

When do you have to decide to use External Racks? Do you have to declare it at the beginning of the attack or can you decide whether to trigger it after your initial roll...like when you add a CF command extra die.

It has the same timing as the CF add die, yes. You don't have to declare it or anything before seeing your result. On the flip side, it doesn't help you get a shot that would otherwise be denied by obstruction because of that timing, such as out the side arc of a HH.

6 hours ago, Ardaedhel said:

It has the same timing as the CF add die, yes. You don't have to declare it or anything before seeing your result. On the flip side, it doesn't help you get a shot that would otherwise be denied by obstruction because of that timing, such as out the side arc of a HH.

Thanks for that Ard. I hadn't even gone down THAT rabbit hole...