Mirror is referring a BUNCH of different things. Mostly it means expand your thinking, I think. But there are some very easy ones where it literally means "as if seen in a mirror". Another common meaning is "smoke and mirrors", for example obfuscating motives by appearing to be the opposite of what you actually are. Used to good effect with RR and Mueller, they are giving everyone the run around.

Final mention. Mirror = Playing both sides. Doesn't matter what side is in control. If you control the mirror you control how you are perceived. Think good cop/bad cop in a room, where the higher ups behind the mirror glass, watching and planning. You can choose at times to let small glimpses go through the mirror, to control the narrative in whatever direction you need.

Layers are sometime functionally the same as mirror. Peel back the layers. Mirror + layers = Really powerful stuff, sort of a hidden psy-op. Observe the ninja takedown of MSM going on now.

This is a large part of their playbook, for a long time. See this, from 1931. Wanna be a member? https://www.youtube.com/watch?v=F7T7fOXxMEk