Boss fights become easier when each attempt has a learning goal. Treat failure as information instead of only as a reset.
Learn one attack pattern at a time
Pick one move or transition and focus on reading it consistently.
Watch where mistakes begin
Many problems start with spacing or positioning before the actual hit lands.
Identify safe recovery windows
Healing and resource use become more reliable once you know when the boss cannot immediately punish you.
Change one variable at a time
Modify survivability, equipment or spacing based on the specific problem ending attempts.