Hmm, don't think it'd be a bit powerful to reroll every 5 rounds?
You get 1 reroll every 5 rounds. Uh, yeah, that's not such a big deal, given that you're practically a straight Binder to get to him at all, and probably don't have any crazy scary thing to be rerolling. I think it's fine. I mean, a level 2 vestige (you can access at level 1, thanks to Improved Binding) gives you a functional Benign Transposition 1/5 rounds. That's not overpowered, not even at level 1. Btw, that would be Savnok, with Move Ally.
All that I say applies only to myself. You author your own actions and choices. I cannot and will not be responsible for you, nor are you for me, regardless of situation or circumstance.