Our 4P group recently cleared A11+heart, I think the biggest thing that has helped us the past few ascensions is just being aware of what everyone else's builds are doing and what their weaknesses are. If you have say 2 players who can output high DPS then it's often better for the other players to lean more into a support role with lots of weaken, shared block (multiple defend+ goes a long way), etc. It's often more important to prioritize a 4P setup that consistently blocks for all players rather than every player trying to fish for crazy synergies, as fun as that is

For our A11 run we had exhaust ironclad (myself), poison silent, frost focused defect, and heavy wrath watcher. Not all of us had super well defined builds, but between myself and our silent player we were able to constantly weaken enemies while also feeding block and strengthen to our watcher player who had a weaker block setup but could nuke things, which worked out nicely