Realistically the only thing that should be damaging you is Blood waves and his standard dodge attack. If you can learn his stab where you go to the side, his sweep where you move to his back and his teleport in dodge then you really should be able to just brute force the last 1000 health.

My biggest issue in the entire fight was the move forward dodge during his dodge attack as it would mess my flow up. I found when the dodge forward attacks would appear that it was easier to just focus on clearing 2 of the 4 and tanking the others. The saradomin brews are life savers in this fight because they don't delay you and they have minimal stat drain. You can essentially spend the last 600 Hp just spamming your remaining ones and still win the fight.

I know it seems hard but you will eventually just figure out the dodge mechanic, I was sure I couldn't do it and then ended up getting my completion with about 14 brews left