Gilgamesh (DLC) was also pain in the ___.
He's got 9999999 health, resets stagger bar after a while, so you never really have time to get high chain bonus, hits hards, removes debuffs etc. etc.
I've only managed to beat him on easy difficulty. :[
You actually beat him....????
I stagger, his weapons break, he seems to heal himself?
IDK I just never beat that guy.
Oh yeah, forgot the healing thing. Everytime stagger ends, he removes all his debuffs and heals himself like 5-10%. So if you actually want to hurt him, you need to remove more than that from his health. At least if you're going to stagger him.
If I remember right, poison works and helps a lot!