I'm glad the last few fromsoft games have avoided these gimmicky fights. They are one of the worst things about early Souls games. I really don't know why they thought these were good ideas.
You have to go towards the boss, avoiding his hand sweeps, and the floor will open up. There's a singular root you can jump on to get to the actual boss, a tiny little parasite thingy.
This is the only difficult boss where I would actually advise AGAINST Havel armor. What worked for me was using the shadow armor + DWGR and rushing straight to each Orb. Easy win
guys you gotta understand that this game is made for masochists who enjoy suffering and pain such as me so if you are not a masochist or you are afraid you might enjoy it kindly piss off