It's the area protected by lots of mines close to the place where you first teleport to from Loic's basement. But what exactly did you do in Sacred Stone when you say you "did everything" there? Because I really couldn't find much to do there at all.
Haha, how the blazes were you supposed to figure that out?!
It was the first thing I thought of myself, I noticed they were conspicuously not-burning.
