I'll search again. and screw it, I'm going to examine the mirror as closely as possible. do I remember properly that the images aren't exact matches in regards to movement?
That is correct. All the adventurers appear, scowling and maneuvering, in the mirror, even if not all of them are nearby. Standing right up close to the mirror, you can see the Descent Pore Array through the archway on which the mirror hangs.
[oh yeah, the other room. I forgot] I walk through the archway wary of those iron bars, if they move to strike me when I walk through, or some other trap goes off, I'll jump back into this room.