u/Emergency-Bid-7834

Say, I want to fight the brigand 10 pounder but haven't killed the brigand 8 pounder yet, will doing enough weald missions make the 10 pounder appear?
I'm currently doing a sort of challenge run where I only get 1 of each hero, and they're all already too high level to fight some of the lower level bosses. The internet is being vague at best, and I don't trust the ai overview