Use the Ectoplasmic Distiller near incorporeal undead to collect 12 Scorched Ectoplasms in Silithus, 12 Frozen Ectoplasms in Winterspring and 12 Stable Ectoplasms in the Eastern Plaguelands.  Bring them along with the Ectoplasmic Distiller back to Mux Manascrambler in Gadgetzan.