Vilestrider Rare Mob

I just cleared a pack of mobs. I go to pick up an Uncut Support Gem (Level 5) and this Vilestrider guy appears out of nowhere. I'm on shocked ground. I die to being one-shot again... I have 1589 life, 1730 energy shield, Max Lightning Resist, and a Remove Shock Charm. This crap is infuriating.

Edit: He has Shroudwalker and Extra Chaos Damage mods. I am also max Chaos Res.