for the 2nd phase (when he is fire) the arrows you have to completely run away from them, you cant roll you have to runI'm like level 65, but i did a strength build so i have no magic resistance. I can get him down to the last little bit of his life but he sends out the arrow attack. If I roll around him to dodge arrows he catches me with the AOE from his teleport. He's giving me more grief than any other boss so far.
dont go near him when he teleports it takes half your health, its not worth the damage you can inflict
heres a tip if you hide behind the pillars you can bait out a slow but powerful attack he will destroy the pillars, dodge that and I think you can attack him
attack his body not the slug tail, I think it does more damage
dont spam roll when those little crystals are coming, they converge near the end and track you so wait till the last second and roll
if you stay near his physical body he will either do arrow (if he does run AWAY and cnstantly move laterally, not in a straight line) if he doesnt do arrows he will do his phsyical swipe attack which leaves him wide open for a bunch of damage if you dodge
basically whenn he does arrows just completely forget about trying to stay near him or attack him just unlock from him and run
you gotta be patient against him