The rules say you can only reroll once, but how does that work with multiple effects that allow for rerolls? As an easy example, say you have a YT-1300 Rey + Fin. You don't have a focus token but do have a target lock. You initially roll 2 focuses and 1 blank. You then use Rey's ability to reroll the 2 blanks (Fin adds 1 more blank) and get 2 blanks again. Now you want to use your target lock....

Are you not allowed to use the target lock due to violating multiple rerolls?

Are you allowed to use the target lock, but can only reroll the 2 initial focus results?

Or something else?

You can spend the Target Lock, but when you choose which dice to reroll with the Target Lock you're not allowed to choose any dice that have already been rerolled.

(If it's super important that you spend a Target Lock for some reason but you either don't have any rerollable dice or you just don't want to reroll any of the dice you have, you can indeed reroll zero dice with it.)

14 minutes ago, Joe Censored said:

The rules say you can only reroll once

Not quite. Specifically, the rules say that any individual die can only be rerolled once. You can play as many abilities as you like, but once a dice has been rerolled, it gains the trail of 'cannot be rerolled', and can't always trumps can .

The hypothetical Predator Han w/ TL could use three "reroll" abilities on a single 3 die attack. One from Predator which could then not be rerolled. TL could be spent and choose one of the remaining two dice. And Han's ability could be used to reroll ALL available dice of which only one remains available.

In the initial example the TL could reroll the two focus dice but not the previously rerolled blanks.

The limit of 1 reroll per die also applies to rerolls from the opponent's dice modification. Effects like R7 Astromech and Zuckuss crew can prevent the opponent from rerolling their own dice.