Retest Now (Horde)

Objectives
Chief Engineer Copperclaw aboard Orgrim's Hammer wants you to throw a Writhing Mass into a cauldron at Aldur'thar. Provided Item:
 * Writhing Mass Banished
 * Diluted Cult Tonic

Description
This should do the trick!

Those twisted hooligans are looking for souls to put in their crazy-juice? Then I say we help 'em out a bit!

Take a swig of this - don't worry, I've diluted it plenty... Its only effect will be to detect any cultist's essence once you've defeated them.

When you've collected a bunch of essences, throw the writhing mass of twisted souls into any of their cauldrons.

Let's see how they like a taste of their own medicine!

Rewards
You will also receive:

Completion
Wahoo!

That'll teach 'em!