Crown of the Lost Conqueror

Crown of the Lost Conqueror is a tier 7 armor token. It can be exchanged in Dalaran for the following items:
 * Valorous Redemption Faceguard
 * Valorous Redemption Headpiece
 * Valorous Redemption Helm
 * Valorous Circlet of Faith
 * Valorous Crown of Faith
 * Valorous Plagueheart Circlet

Source
This item drops from Kel'Thuzad in the 25-man version of Naxxramas.