Chestguard of the Lost Protector

Chestguard of the Lost Protector is a tier 7 armor token. It can be exchanged in Dalaran for the following items:
 * Heroes' Dreadnaught Battleplate
 * Heroes' Dreadnaught Breastplate
 * Heroes' Cryptstalker Tunic
 * Heroes' Earthshatter Chestguard
 * Heroes' Earthshatter Hauberk
 * Heroes' Earthshatter Tunic

Source
This item can be found inside the Four Horsemen Chest after defeating the Four Horsemen in the 10-man version of Naxxramas. It can also drop from Gluth.

This item is also sold by the following vendors for :
 * in Dalaran
 * in Dalaran