Hi,
after several playthrougt, I have to say this boss is very clunky for MELEE build. It usually goes like this:
He drops lava pool in front of him, but it extend too much. You still got damaged if you move behind the boss. So you move away to pull him.
That’s when he spit fire. You move to the side and wait.
The pool disappears, you go in, hit twice
repeat from the 1st step.
We meet him quite early in the game. His fire damage is unusually high comparatively to previous boss (even more in masochist mode) while the fire resistance is on the low side. Face-tanking is not an option.
All in all, the fight ended up having more downtime than action.
My suggestion: Shrink the lava pool a little. Just enough so we can be safe behind him.