Bunch of people called me a liar when I said this was achievable. Here you go. 8k ES on mapping set with Essentia Sanguis for ES leech. Set 2 for just raw ohko power (has fewer def points and Cooked in it hence the reduced defences). Uber Arbiter's health doesn't fully track all the damage here because it caps at his max HP (22mil).
No Adorned, HH optional (uses the low life belt), no buffs like Mark / Shock, no Snipe.
Guide: https://mobalytics.gg/poe-2/profile/iron-robot-nkqkz3/builds/659feb31-3e13-444f-a848-5f0f2a8af4e4
Can be played with any martial with ease. Will update for 0.5
Here's a 6man Uber Arbiter with the same build using crossbow: https://www.twitch.tv/gl1tch3d/clip/AntsyEasyLaptopSoonerLater-Cjam5fthZTjObTDF (done with tabula)
edit: Where ninja? Sorry - I actually keep my ninja hidden for most of the league. Unfortunately a lot of stuff gets sniped while I'm testing stuff and I get endless "why did you change this" messages when I have a slight variation that isn't in my guides.