Ahahah I can't believe this...it was easier and faster than NM!
This is how it happened:
merc died immedately but with the new build Decoy could bear 2-3 hits and valkyrie aswell (lot more if it happened to hit the chance of casting her from 'Peace')
I just kept him busy with decoy/valk all the time, firing GAs...the huge mana leech allowed me to always have enough mana to summoning them...as soon as I hit the ctc Valk, used 'the bonus time' to switch to javelins and fire everything till I went out of mana
Then switched back to bow and repeat.
I went to town 2 times to restock arrows and used in the whole fight 0 life pots, 8 mana pots.
Bad drop? Who cares! Now I'm pretty confident to reach act 5 at least