Try if you can get the completion rewards of the cav quest. Rest I’ll say Continue with story mode progression… act 6 is easier than before and you can beat most of it with an average roster, some fights do require specific counters like 6.2.2 sinister, 6.3.1 medusa, 6.3.6 cap so make sure you have those before jumping in blind. Grandmaster fight is a test of skills so be prepared for it. Then act 7 is pretty fun and bears good rewards as well… good luck👍🏼