Champions unlocking

Im now 5400 trophies and have all Cards exept monk - i have already unlocked all 4 Champs
If i now buy a legendary kings Chest, do i get a champion or not? I know im not in the Arena however i already have these 4 Champs so how does that work?

You should — chest unlocks look at player’s card collection for what is unlocked / avaialble.