I haven't played any super difficult games.yet but
Spoilers for TotK
Demon king Gannondorf is a really difficult boss until you learn his attack patterns (he can flurry rush you!!!!!)
when i did the fight he just dodged my attacks so can he actually flurry rush???
Third phase (after you help him get his health bar down to a reasonable size) he dodges your flurry rushes, and then rushes you. You need to dodge *that* attack to hit him