[3.10] Durimon's COC Ice Nova Assassin, New Way of ES & DPS Balance, 8 ex for 100% Delirium

Hey man I actually went to convert my BV assassin to your build. Shreds typical map content real fast but have a little bit of an issue with survivability. I also noticed that in your video you somehow achieved 4k ES, but in the PoB which I tried to replicate for my build, I could only achieve 2.7k ES. Is there something I am missing?

Here's my PoB: https://pastebin.com/Tu1JPqNA
Thanks in advance! Kamsamnida!

Edit: solved the ES part, up to 4.1k now, but definitely not tanking anything well caause I'm getting one-shot by plenty of things. Doesn't even seem like an armor or phys reduction issue - just feels like there isn't enough ES in the pool to begin with ):