i believe that the a2 merc has to kill an enemy before it even pops its aura....so on pindle runs, it comes down to tanking... a5 is better. here is what my barb uses...

Hmasues Adamament (sorry for the butchered spelling, too lazy right now to care)
shitty Arreats
Flamebellow Balrog Sword.

He has no prob in hell meph... hardly even loses life.

HOWEVER, my merc is only for botting/mfing. Rushing and lvling and whatever could have a better Merc/sorc combo. Just my input

EDIT: Oh and since he said he is a COLD sorc, i dont think he needs more cold spells (a2 Holy freeze or a3 cold).