Benedict Silver Kin - Holy Caves

I got through the entire Holy Caves dungeon and ran into Bendict Silverkin. I could not damahge him! How do you kill this guy?

Thanks for any help you can provide.

He procs invuln and has high regen, so it's a dps check.

Summon: Ill foe or prestige abilities like bleed will really help!

TY for the tip!!