When he rejoins the Order in the middle of the Clone Wars, all Ferus wants is to help as many people as possible. An emergency mission lands him in control of the 501st before he even has time to catch his balance, though, and the disappearance of the Chancellor means there's no time to waste. The galaxy's Deep Core is a treacherous maze of deadly planets and old traps, and fighting their way through is the sort of thing that would push Ferus to his limits, even without a squad of clones to protect at the same time.