Arcane Quickener

Arcane Quickener was used to cleanse the cauldrons in Western Plaguelands. Since the cauldrons and associated quests were removed in Cataclysm, it no longer serves any purpose.

Source
Arcane Quickener is sold by Alchemist Arbington at Chillwind Camp in Western Plaguelands for Alliance and Apothecary Dithers at the Bulwark in Tirisfal Glades for the Horde. You must have completed the Cauldron quest line to purchase this item.

As a quest objective

 * Felstone Field Cauldron
 * Dalson's Tears Cauldron
 * Writhing Haunt Cauldron
 * Gahrron's Withering Cauldron