For people having real frustration with this boss, just use the Mist. If you don't have 30 intel to use it, respec your character, use the tree branch staff for faster casting, stay close to him and just keep him in the mist and avoid his attacks. Then you can go and respec your build back to how it was. You can also use the infinite respec glitch if you only have one more time. So just stack fire defense (flame stone plate, red bug pellets), use a fast cast staff, use the black knight shield if you can, if not the dragon crest works as well if fully upgraded and this hard boss fight becomes much more manageable, especially if you have Shira with you to distract him while you are casting this mist. I'm playing NG+ 7 and it's not been a problem. Only issue is the lazer attack in stage 2, if you are not under him, in his ball sack, it's like 50/50 you will get one shot. Still a totally manageable fight and really the only use in the game for Pestilent Mist. This is also a very effective way to kill him on the bridge. Mist on, Mist off.