If you are watching this you are probably like me trying to get infinite FP tear but cannot defeat this boss. I found it more managable with this trick.
0. put all flask to the FP one (I have 8). My mage build can't even take one hit anyway.
1. Go along the right cliff; avoid the monster that transforms into a giant.
2. When the boss is triggered, sharp left and head to the corner where there's a small step.
3. Go down the step and see if boss move back, if not, circle up the step and jump down again. (The boss is slower around the step and it almost never directly move up the step.)
4. If boss start to move backward after you jump down, wait until it's almost back under the tree and jump up the step again.
5. The boss should come at you with the spiral attack, cast two Magic Glintblade and jump down.
6. Most likely the boss will just move backward, repeat these steps and it took me about 10 min. It takes some patience.
(interestingly when it move backward, it got burnt by the bonefire too)
![](https://i.ytimg.com/vi/BeBaURulmbw/maxresdefault.jpg)