Rules and Errata

Obviously, the reward should be:
"For the rest of the Adventure Path, after you rebuild your deck, you may banish a card from it to choose a card from the vault whose level is #-2 (minimum 0), then add it to your deck . Adventure Card Guild players choose the card from their deck box instead."

MatsuKurisu
Agree with Nickademus's suggested wording
"For the rest of the Adventure Path, after you rebuild your deck, you may banish a card from it to choose a card from the vault whose level is #-2 (minimum 0), then add it to your deck . Adventure Card Guild players choose the card from their deck box instead."

It should also be "whose level is #-2 or lower (minimum 0)", so that at level 5 you can pick a 2 or whatever.