[ This is a good time to wish he stayed in school... but also, Mercury? Let him remember which exact planet that is in the back of his head (not Earth, he knows). ]

Is it at a baseline? Isn't some parts of the cities worse than others? The Moon having something to do with corruption sounds possible if we have stones from it, but-- wait, [ wait wait, ] there's something other than Lunar Orbs?

[ He's figuring on the spot he doesn't know which stones the man means, and almost thought he meant bloodstones to begin with. But now he's a furrowed brow, thinking--huh? ]