Tearing my hair out over Lord of Vampyrium boss

Getting wrecked trying to finish this quest and need some help. I've checked the guides, I'm doing dual handed magic at level 97 magic and 98/99 con/defense. Overload potion and o'log baths ahead of the fight. (Monolith powers set with extra hp, death ward, and berserker ) Set up the suggested revo bar, and I got to the second to last level after you go through the portal and have no allies and 35 losses later I'm about to rage quit.

I tried deflect melee prayers, various ancient curses (soul split), etc. The crazy thing is the first 2-4 tries I got pretty close, sometimes got him under 10k health before dying. I feel insane because it really seems like it's gotten harder/he's hammering the special attacks faster the more times I go back. I'm getting wiped without barely touching him/Anticipation/Freedom never seem to help. Specifically the 'you cannot escape the darkness' thing where the screen goes black and then I'm suddenly down to under 10% hp happened about 4 times in the first minute of my last attempt.

I feel like I'm missing something, would love some advice. 🙏