Who do i rank up for act 6?

1bzz

Haven’t touched the game in ages and I came back to start act 6 content, which i noticed had been reworked, but i’m getting destroyed in simple chapter 1 fights. My roster is super extensive but i have no 6* above rank 3 purely because i don’t know which ones to invest my limited gold and catalysts into for act 6 content.

Most notably I have 6*: mole man, human torch, magneto, nick fury (rank 2), dr doom (rank 2).
any tips on who to rank up is appreciated this is a huge roadblock for me in progression.
also any tips on how i can get iso8 are really appreciated bc it’s looking sprace from my hiatus