Chaos Mod Overtuned

I just attempted a Tier X map where monsters got Extra Chaos Damage. I have max chaos resist, 1500 life and 2500 energy shield. The first mob in the map was a boar that charged me. My energy shield was down. The first attack one-tapped me.
I am level 75. Something is not working right here. Difficulty is fine but I shouldn't get one-tapped by the first mob in the map with a few divines worth of investment on a character and resists capped...