Gahrron's Withering Cauldron

My analysis is complete! The blight that affects the animals here is no residual disease. No, it is something new... and I think I know what it is. The Cult of the Damned maintains a plague cauldron on a farm called Gahrron's Withering. This farm is due southeast of us, close to where the Eastern Plaguelands begin. I need a sample from this cauldron to verify my suspicions. Eliminate the cauldron lord present there for its key. You will then be able to access the cauldron and obtain my sample.