Nameless King…

I’ve come to the conclusion that the Nameless King is impossible. His 1st phase I can do no problem whatsoever. I don’t even take a single bit of damage. But then comes phase 2 and he just has some kind of hacks. I can’t even roll to avoid him or back up to drink Estus. Dude just has infinite FP and Stamina. I’ve beaten the Soul of Cinder. Done every other base game boss and a couple DLC bosses. Nameless King just can’t be beat. What do I do? I’m banging my head against the wall here praying to the sun and nothings working.