Sir Automatronicus

Is anyone else having trouble beating him in the Restricted Elementium dungeon?

He is level 120 with a level 7 life rune - and SP have put all of his self-heal skills in the AI pool. So even when he is possessed (even mega possessed) he just heals himself and removes the negative effects (including torture like bleed and burn).

I think this is very clever from SP so I actually changed my own Sir Automatronicus skills to match... a viable tank if you cannot even keep it possessed.

I know I need a big magic attacker (Shademoon?) but the restrictions are Good Legions/Undead and something else, so I don't have many options against Metal.