I did it by baiting his "Self Immolation" move.. if you stand uderneath his belly he will most likely use that move, then run to his hind left leg and attack him.. as long as you stand at the outer side of his left leg youre free to safely hit him (his right leg is NOT safe). The only other moves he used were ground stomp (which was completely useless because he used his front claws) and rain of fire (which can be easily avoided since you are already very close to his tail). Pay attention after he lands after his rain of fire, where he might use his hind legs for ground stomp, which will kill you if you are in front of his leg.

Rain of Fire CAN kill you while you're outside of the fog door. I was summoned as a phantom looking for an oportunity to enter after the host and I got killed without pressing the prompt button to go through the fog.

My set of Smelter Demon Helm, Chaos Robes, Smelter Demon Gauntlets, and Chaos Boots only add up to 294 fire protection all at +5

Big Toe and Gower are total crap. Ancient Dragon still takes off and ring just doesn work. Bait and dash makes a lot more sense.

900 fire resist works very well, fight is trivial then and you can study his attacks at leasure. Finish old Iron King DLC first to get Pharaos Mask, Fire Resist Ring +3 and Dispelling Ring +1. Wear Chaos Set and use Flash Sweat Pyromancy,

I beat this guy my second try rn, I used a lighting infused Murakumo +10 and as for fire defense I wore a Flame Quartz ring +3. Also some Smelter Demon armor. Nothing too fancy, and not much of a "set". Didn't use pyromancies or spells. I did summon Vengarl who can be found just outside the door tho. tried to stick to his back feet, alternating between the left and right every two hits or so. Which helped keep him from spitting fire. Vengarl died really quick, so not sure if he helped or not. Also I'm not the very best player, so If I can do it, you can too lol Good luck!

I'm geussing thorned greatsword (aquirred from ornifex with looking glass night soul) will do lits of damage because of lightning stat but I would reccomend using rb for attack or having lots of repair powder because normal lighning attack well reduce durabilty by ALOT!

I dealed very fast with him with a thunder greatsword +10, gyrm greatshield +8, smelter set with sinner mask, third dragoncrest ring (this was very needed to be able to stop his rain of fire with the shield), cloranty ring +1. And for magic i used dark sword and crystal sword. I made 800 - 700 damage each hit, so he didnt last that long.

I remember having problems with him in vanilla. But in sotfs I beat him on a 2nd try, since leveling is faster and you can do dlcs anytime. So I was like 195 atm and beat him in 3 mins.