Final boss from final fantasy 4 on gameboy advance, I loved everything about the game, but the boss was too difficult for me at the time and I got bored of grinding. This was back in middle school era.

I should go back and replay the game now that I’m older and have more experience with rpgs.

More recent example would be final boss from tunic. I don’t think I got enough power ups when I got to the final boss and struggled hard against it.