I just played The Hills of Emyn Muil last night and had a question. Before I get to the question, though, let's start with what we know. If Amon Lhaw is the active location, you treat attachment cards as though the text is blank. So if it's the active location and you have Ancient Mathom on something in the staging area and Northern Tracker clears that location, you're out of luck because you lose your Ancient Mathom without the card draw.
So what if your Ancient Mathom is on Amon Lhaw? At what point does the Ancient Mathom regain its text? Can I draw cards after Amon Lhaw is explored? Or does it not trigger because the Response effect is missing unttil after it is already explored?