PoB: https://pastebin.com/B07dREGg

I'm really glad I didn't sell this build yesterday, I did a bit of upgrading/fixing and now it has both damage and bigger immortality window (which is all the time while leech instances are up, so as long as you're hitting shit and leeching life off it - you're immortal, literally).

I haven't done any sim farming, but I've tried it a little while ago and bricked it because of the Leech debuff.

I think in terms of math, my total life leech should be 2x+ of my HP for the immortality to work, at least that what I've seen when fiddling with the tree.

This version is immortal to all types of damage by the way, not just phys like the Jugg, but I'd say jugg is probably easier to play since you don't need to worry about losing at least Phys immortality. With this build you can facetank literally everything there is in the game as long as you're leeching.