Corpse Dust
From WoWWiki
Corpse Dust is used by death knights as a reagent to summon a ghoul without having to use a humanoid corpse.
Source
Purchased from reagent vendors.
Patches and hotfixes
Patch 3.0.1 (???): Added
Corpse Dust is used by death knights as a reagent to summon a ghoul without having to use a humanoid corpse.
Purchased from reagent vendors.
Patch 3.0.1 (???): Added