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.
As an ingredient Edit
Patch changes Edit
TBC Patch 2.4.2 (patch date::2008-05-13): Prince Kael'thas will now drop Primal Nethers in Heroic Magisters Terrace.
Primal Nether did not previously drop from Kael'thas and was not considered "broken".
TBC Patch 2.4.2 (patch date::2008-05-13): Primal Nethers will now show up under the Materials subcategory in the auction house.