What is the 3 (next to the cost) for on this Echo Base trooper card for? I am confused with this, because I know the Imperial player can spend threat to bring back in figures, how does this apply for the Rebels?

I am a new player and have not played that many games yet, still reading the rules. Thanks

This can effect certain command cards in skirmish - not really used in campaign.

How is it used in a skirmish?

How is it used in a skirmish?

I think there are effects that trigger on units "with a reinforce cost of X"

If you want a specific example, the command card "Reinforcements" says:

"Use at the start of the round. Choose 1 of your defeated Troopers that has a reinforcement cost of 3 or less. Place that figure adjacent to any other figure of it's group."