Corpse Wax

Corpse wax is a quest item.

Source
Corpse was can be found on undead throughout the Hidden Vale, but is most common in the ruins of Ravensmoor. Lord Enmar will pay adventurers for battling the undead if they bring him corpse wax as proof of their deed.

Trivia

 * During Release 7, ectoplasmic residue could occasionally be found. This was replaced by corpse wax, as the former name was not "gameworld compliant", likely due to the Ectoplasm reagent.
 * During Release 12 due to some pranks with Corpse wax bought at vendors, Lord Enmar is no longer accepting Corpse wax as proof of slaying undeads.