Necrophile Tome: Corpse Exploder

Necrophile Tome: Corpse Exploder teaches death knights the Corpse Exploder ability.

Source
This item can be purchased for from the following vendors:
 * Dread Commander Thalanor in Acherus: The Ebon Hold above the Eastern Plaguelands.
 * Quartermaster Ozorg in Acherus: The Ebon Hold above the Broken Isles.