Shameless self-plug, but this one is pretty tough to crack. Sports over 4k hp regen and around 800k retaliation damage on (mostly) affixless greens and faction gear. I am sure it would work mostly as a passivist as well. It is not killing regenerators though, so I am pretty sure it does not clear all content, at least without getting some nice drops. I hope to finish leveling it someday.