https://pastebin.com/EmH1QmP8

CONCEPT: Build uses Overflowing Chalice Flask along with Olroth's Flask to perma sustain Ward. Note the flask uptime is 100%. We convert ALL damage to Fire and mitigate fire damage so much that nothing can exceed the ward. Only damage you take is DoTs, discussed further below.

Go CI for chaos immunity.

Convert 100% Cold and Lightning damage taken to Fire via Sublime Vision + Dawnbreaker + Tempered by War. Get 90% fire resistance (Tree/Clutsters/Gear).

Further 60% of Phys is taken as Fire (Including Dots) via Cloak of Flame & Dawnbreaker. Additional 40% phys taken as fire on gear, timeless jewel notables. 100% Phys hits as fire (60% phys dot as fire). The ONLY damage type you take is fire (reduced by ~95%) and 40% of phys dots as phys dot.

You need to get about 200 es on it somehow (small clusters, abyss jewels, rings, etc.) and you should be immune to all damage except phys dots, and for phys dots it would have to be a massive dot to kill you. The ES is only there for DoTs, which would all be taken as fire and reduced to about 5%. For hits, I don't think there is anything in the game that can penetrate your ward if you have 1000 ward.

Would be interested on thoughts and ways to optimize for full immunity. Can't think of any other way to reduce Phys dots. Note that there are very few sources of Phys dot outside of Bleed/CB, and if you avoided those sources you would essentially be immortal.

I think we sacrifice a bit of DPS and get more ES & some regen to mitigate DoTs completely, resulting in full damage immunity. Belt, rings, amulet, and jewels could confer a substantial amount of flat ES, with some source of recovery it should be enough to mitigate dots entirely. Requires some testing and tweaking but the concept is sound.

DISCLAIMER: Since some people seem to think I'm "advertising" something, let me say this build is not complete DO NOT REPLICATE THE POB as is. I did not claim the build in the PoB is immortal, the concept is if we can solve a couple problems, namely DoT weakness. There are items missing, 11 passives missing, and several options for gear selection. It was posted to garner a discussion and flesh it out with ideas that I may not have considered. I'm not looking for an opinion on how X build is just better, but ways to make this one better and playable.

EDIT: This build is also possible with Mahuxotl's Machination instead of the pricey Sublime jewel. If we can solve the DoT issue and figure out the best way to add some ES I can retool the build for Mahutol's to make it cost less than 30div potentially.