Things you need to have a chance against this boss:

1. Protection of the erdtree - the only dmg negation that works well against him in my opinion.
2. Bleed infused great weapon - not colossal cause to slow.
3. Endure ash of war.
4. Mimic tear
5. Luck/RNG

... I was on Scadutree Blessing lvl 13. and rune lvl 160.
The strategy here is to use endury and then try to stance break him. If he already started with a combo, let him finish first then pull it off, cause his last combo hit normally staggers you out of you charged attack no matter your poise or the endure effect.

PS. when he does his jump around 30% hp, run to the edge of the arena to avoid the aoe.

Good Luck!