My merc is Act 2 Nightmare Holy Freeze, and uses Shaft, Tals Helm, and Cruel War Pike. No Mf, but his reason was to solely take shots and dmg Pindle a little.

Barb mercs are better, because my merc never gets off his Aura in time, and if he does, its pointless by that time! LoL, doh!

If you keep that merc, just put on Skulldirs and socket the Doom with Amn or something for more life leech. They aren't hard to get, so Amn won't really ruin it.

He will stay alive quite fine I'm sure, but that every so often case, just set your chicken lvl on him too!