To tell you the truth, adventurer, I've never seen any plants like this in my travels. Perhaps I should take a trip to this crater... At any rate, I think I know just the thing Muigin's looking for -- Atal'ai haze. It's horrid stuff, hard to collect, but it's just what he needs to control the little monsters. You'll need to visit the temple of Atal'Hakkar in the Swamp of Sorrows. The Atal'ai Haze can be collected from the deep lurkers, murk worms, or oozes found there. Good luck, adventurer!