long ago i saw a video of a wizard abusing force armor and life regen to be invulnerable. it was before the nerf, but i think doing it is still doable.
when you get hit with force armor, 4 things can happen:
damage < 35% of your hp, force armor does nohing.
35% < damage < 135%, you get hit for 35% of your hp.
135% < damage < 200%, force armor reduces the damage by 100% .
200% < damage, you die.
with very high life regen (1500+), we want to have the least HP while maintaining our EHP. this way we can take hits and heal in 2-3 seconds, and with some kiting skills, become kind of invulnerable.
the most damage you can take from hard to dodge attacks (elite phase beasts and elite act3 shamans) is around 130k.
we want our ehp to be 130k/1.35=96k ehp, so we can take 3 hits in a short period of time (more hits in longer periods). this can be done with 3400 base armor, 650 all resist and only 12k hp, which is 340 vit. THIS IS ALL WITH GLASS CANNON! with ~2000 life regen, you can take 1 hit every 2 seconds and heal back.
these stats are high, but definetly not godly. you only need around ~215 vit on your gear, so the pieces are not that expensive either.
my wizard ('hatotah') is using this tactic, currently for act 2 (just leveled him). all of my pieces cost less than a million, except for my weapon which i borrowed from my monk. i have ~77k EHP with 12k hp, which means some things in act 3 will 2 shot me - still better than my demon hunter who also gets 2 shotted, but doesnt heal back in 5 seconds!