Retest Now

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... I'm almost positive that its only effect will be to detect any cultist's essence once you've defeated them. When you've collected a bunch of them, throw the writhing mass of twisted souls into any of their cauldrons. Let's see how they like a taste of their own medicine!

Writhing Mass Banished