Carapace of the Old God

Husk of the Old God is a Brood of Nozdormu armor token. It can be exchanged along with various idols and scarabs at Vethsera inside the Temple of Ahn'Qiraj for the following items:
 * Conqueror's Breastplate
 * Avenger's Breastplate
 * Striker's Hauberk
 * Deathdealer's Vest
 * Stormcaller's Hauberk

Source
This item drops from C'Thun in the Temple of Ahn'Qiraj.