How do I progress?

I'm using the Maxroll Lightning Arrow build and feel like I've hit a wall. I can clear t15 maps quickly and one-shot level 80 map bosses, but I can't kill pinnacle bosses yet. Gear upgrades now cost several Divine, and farming the number of divines I need feels impossible. I've tried farming Trials of Sekhema, but I can't quite finish the last phase or boss.

What should I do to progress?