Medallion of Karabor

The Medallion of Karabor is an epic necklace that provides stamina and shadow resistance. It was originally held by draenei priests in order to allow them entrance to the Temple of Karabor. Now it serves the same purpose for adventurers seeking to challenge Illidan Stormrage, who has taken residence in the Temple of Karabor - now called the Black Temple.

Source
This item is a quest reward from A Distraction for Akama.