Can someone tell me how to beat boss 34... ㅠㅜ

I think it's Behemoth, but you definitely need to have the 'Peony Keepsake' (Stage 3) to endure the painful patterns.

You can see your play records, and use them as a reference for your deck. You'll get the hang of the patterns after a few tries! I'm currently challenging the 46th boss on Hard, and I cleared it on mobile just by referencing the deck. It's fun to clear stages like that, one by one.