Primal Nether

Primal Nether is used in epic level Engineering, Blacksmithing, Enchanting, Jewelcrafting, Leatherworking, and Tailoring recipes. As of Patch 2.4.0, this item is no longer Bind on Pickup.

Source
This item is a guaranteed drop from the final boss of every 5-man instance on Heroic mode. It also has a low chance to be an additional drop from the final bosses of high level dungeons.

This item is also sold by G'eras in Shattrath City for 52 Justice points.