Finally got Chewie to 7*.
After hundreds of attempts with zBossk lead and getting absolutely nowhere, I found all the potency I could find without sacrificing too much speed and loaded up a g11 Boba lead (no zeta), g12 Bossk, g11 IG88, g11 Dengar, g11 Greedo squad.
About 5 attempts later, Greedo landed 7 crits and burned Chewie down. Then I took out Lando, then Han, then Leia, then r2. IG88 and Greedo went down but they did their job. And Dengar got shot first by Han and stopped r2’s stealth.
It was a pure RNG fest but I managed.
Total potency across all BHs was around 400-450.