watch this video.
He says that get magic find from you merc when it kills the mob/monster/boss
so load it up with MF gear on an enchantress
so you'd place points into warmth,enchant,fire mastery, and static field
make it a barbarian merc
Immortal King's Will helm "LK" helm with two ists
eth Skullder's Ire "ist'
180% 6 Socketed sword with 6 Ist Runes
that's a total of 418% extra magic find when your merc kills the boss