I don't know about you all.  But I have had super good luck with an ARC witch, Multen shell,  displine, I also use -light curse, forgot name lol!   But good lord it can do dom runs in 7 mins no problems.  Lvl 72 maps 99% time easy.   7k arc,8k multen 
  
3k life 3k engery sheild seems to be the sweet spot with 45% mana sheild regain faster added.  Have pots set to 80% life 20% mana You do need a 6link armor to get mana,life,penatrate,Arc,Echo,Faster Cast  Seems to rock.  I used Fire penatrate,Reduce mana, Multen shell, Increase Burn Damage, In 4 link gloves,  Increase area, Faster cast, Reduce mana, Conductivity in 4 link boots.  You need faster cast to not slow your main skills down from firing.   
  
  
Life leach and mana leach pretty much keep my bot 80% to 95% full life with arc even under super heavy fire. 
  
You need an item with!!! Can not be stunned! 
  
  
I mean god it works great for me tree is simple basic arc witch build.  I have 300 mana after arua.  Mana leach keeps it full easy!  I know you all goign to tell me arc witch suck but gg they clear maps fast!