Death Knight Cavalier

Death Knight Cavalier can be found in Naxxramas. After killing them, you will then have to fight the Deathcharger Steeds that they ride.

Notable loot
Like all trash mobs in Naxxramas, Death Knight Cavaliers have a chance to drop the following:

Normal mode

 * Omen of Ruin

Heroic mode

 * Shoulderguards of the Undaunted
 * Ousted Bead Necklace
 * Shadow of the Ghoul
 * Boots of the Escaped Captive