Two-handed a washing pole+10 with golden pine resin, and cast Flash Sweat every now and then. Since there's only 4 casts, when I'm out I use Small Orange Burr. I can't dodge the flame consistently enough, especially when he's too close to the edge and I can't run towards the tail, so this helps me survive the fire even while slightly Hollow (I had died 3 times since last effigy but with Life+2 and 3rd Dragon ring I still had enough HP at 43 VIG) .
What sucks is that while the Washing Pole is the strongest weapon I have, it has the worst durability ever (20), so mid-fight I need to replace it with my Blacksteel Katana+10. Luckily once he leaps for his AOE, if I successfully run away to dodge it I do have time to go in the menu and swap it out, I just skip attacking on that turn.
With Flash Sweat active, I need 1 Estus + 1 lifegem to fully recover my health (risky, sometimes I barely have time to heal before he leaps up for his AOE again); with Small Orange Burr active, I need 2 Estus. I even hotkeyed Divine Blessings (figured it's the time to use them

) but didn't need them, I finished the fight with 1 Estus left.