I killed him with barb, soon after hitting 120. Didn't stack any resists, didn't optimize gear.
Just ran around with fortress. I could take damage for maybe 2s if i tried to tank it, thats enough to run around him at certain distance, to make fortress target him (you must see him for that to happen). Around 10min of that, with wolf stance, cb helps, he dies. Felt really easy, overall easier to do than previous patch.
This will work only for chars that can deal damage passively to him though, via trap kind of skill. If you have to tank him to damage him, then you need proper gear. Or possibly for trophy farming, being immune to his attack would make this faster.