Hallowed Husk challenge in Abyss

Any tips how to do the Hallowed Husk challenge in Abyss? I have 12k ES but I can't survive 5 stacks of blood rain.

I bought Infinite Pursuit boots and activated Soul of Arakaali and Soul of Ralakesh. What other ways are there to mitigate the blood rain damage? Obviously I'm not asking for bleed immunity since that would ruin the challenge.

You don't have to survive it for very long. Just get him very nearly dead, then wait and kill him as soon as you hit 5 stacks. Use something long range with culling strike to guarantee the timing if you want

Well the problem with that is that I'm using totems. It's very difficult to get him to LL without killing him. So I need to survive it for longer time. :-(

I tried with off hand culling strike tornado shot - I switch to that when the boss is low. But there are too many mobs who kill me way before I reach 5 stacks of blood rain since the rain isn't up all the time.

Tried several times but I just cant pull it off. Either he kills me or I kill him by accident without the stacks.