This guy is H A R D more harder than the final boss let me tell you but if you have the patience to spare you can survive him, so let me tell you how i did it, first of all you need to prepare with several things, get anti burn medicine, the Suzaku shield (VERY IMPORTANT) and the maledict finger whistle (you get it by defeating the second guardian ape then coming back to defeat the shaman), also max the spiritual emblem skill, and VERY VERY IMPORTANT buy the Spiral cloud passage skill from the jar noble in fountainhead palace, this attack will help you even vs isshin because it hit hards, it hits plenty and it doesnt need spiritual emblems to use it ok lets get to it
First phase: you have to wait until he do his three hit combo, you will notice it because his arm will begin to burst in flames when he is going to do his third attack RUN TO HIM DIRECTLY AND TO HIS LEFT, you will be unharmed and can nail a spiral cloud passage in his legs for more damage, if you see that you can't make it, counter the third slash (is a overhead one) with the Suzaku shield, that will stun him, keep slashing him until he does three things, he will jump backwards to evade you, he will try to stomp you but you can parry his feet or he will try to body slam you and create a shockwave, just jump it and grapple him to avoid damage and slash him some more until you deathblow him, he can also do the third slash without the other two, you can do the same trick, dont go to him when he throw himself to the ground, dont risk cheap shots you need to deathblow him three times so wasting health is not a option, if he try to ram you with his attack where he is dragging his left arm just jump, yeah just jump i think is a bug but even when actually touch you when you are jumping you will be unharmed
Second phase: he get two new attacks but both are easily avoidable, first he will burn the ground very extensively but you can evade it by jumping to the sides or if you are nearby you can grapple him the other is that he is going to throw some kind of fire rocks but only run toward him to get a cheap shot at him and keep running until he stops, he will keep his old attacks remember the slashes
Third phase: this is where shit hit the fan but with :TACTICS: you can survive, he will try to encircle you in a zone full of fire, when he begin to create it he will do a swipe attack jump it and then run out of the fire field, this is important because the space inside the fire field is to narrow and it will be for all purpose a death warrant, just get out of there and keep the same strategy as the other two phases, when he has like 1/4 left of his health he will become relentless but thankfully we are prepared arent we? get close to him and use the maledict whistle finger, that will stun him and then keep hitting him with everything you got, if he recover, stun him again you can do it three times but two will suffice
