The best way to farm Dire Maul West, the Treants/Gaurdians, Ironbark Protectors, Arcane Abbarants, Mana Remnants, and Ghosts, all solo-able by Ranged classes. You can pretty much clear every mob in the first room you enter.

Mobs drop: Libram of Focus, Essence of Living, Greens/Blues w/ Nature Resist, Vendor Trash

Try it while it lasts because this has been already found out on the Mage forums and it will be nerfed soon anyways. The Librams will probably lower in price significantly as well since next patch, the ZG enchants will no longer require Librams from Dire Maul..