Elden Ring. Commander Niall NG+7

I HATE this boss with a passion. I messed up by trying to punish him after his charge a bunch of times too. Skill issue on my part. I used a lot of heals too but at least I only mistimed one of them.
I also experimented a little and tried using the Crimsonwhorl crystal tear in my physick to convert all damage taken into health for 15 seconds, but apparently it only restores 5% of your max HP when you take a hit. USELESS.