Doom is a runeword, about 1/4 the way down this page:
http://www.battle.net/diablo2exp/ite...ords-110.shtml
I have an act 2 merc from nm with my barb and he kicks *** with this weapon. Usually my barb dies from an iron maiden spell before the merc does. I don't have the best armor, rockstopper helm and 1400ish armor that is nothing special but it works.