Ectoplasmic Resonator

Source
This item drops from: providing you are carrying a in your backpack. The best place for them to drop is around Gahrron's Withering
 * Hungering Wraith in Western Plaguelands
 * Dreadwhisper in Western Plaguelands
 * Spectral Attendant in Western Plaguelands
 * Araj the Summoner in Western Plaguelands
 * Cauldron Lord Soulwrath in Western Plaguelands
 * Haunting Vision in Western Plaguelands
 * Eye of Naxxramas in Stratholme
 * Wailing Death in Western Plaguelands

Use
The above ingredients are needed at the Scourge Cauldron for the quest