Some tips
-Completely ignore the spiders. If you time it right, you can get 2-3 hits in before they even react. Wait for even a small gap between the larvae and its goons then go for it.
-When Rom uses its raining icicles attack, sprint as fast as you can in any direction. Works every time.
-As its health gets lower it gets defensive. When it swings its tail/torso upward GET BACK. Also when you start hitting it, it'll start swinging its body at you so roll away after around 2 hits and repeat.
So run and don't dodge? Thanks, that;s the only thing I'm taking damage from.
Still hate that I'm farming vials though... BB feels like a huge step back from DkS in terms of health management and co-op. Whywould I ever use my own vials when helping someone? To get some insight? Eh, not worth it unless my stash is full.