This is a Third Eye exercise, designed to open the Third Eye, and it is useful for enhancing the process of integrating the collective consciousness. It will give you an opportunity to give love to the aspects of your greater, collective Self, as faces that are not your own, appear as your reflection in the mirror. Some of these faces will probably scare you, it is an opportunity to give love despite fear. If you become really spooked by it, then stop, turn the lights on and get grounded. If you have a tendency to paranoia, then this meditation is not for you!
I call this meditation "The Mirror Game", and enjoy it as a "Kundalini party trick." Fun to do with other people, at parties! All of us gathered in a darkened bathroom, meeting alternate aspects of each other, or facing each other in a circle, with the lights dimmed. As you do this game, you will become unified with the other people you are doing it with, and you will actually start seeing the same things.
In the twilight, when it's dim, it's very easy for your eyes to play tricks on you and that's what we want. We want tricks.
I have fun with it, I treat it lightly, because I find a casual approach is less intimidating and scary to people... but the use of mirrors and similar exercises have been used for serious magic, for thousands of years. There is quite some power and history behind this game. The oldest Celtic burials show that each person was buried with a scrying mirror, not clear enough to actually use for examining your physical appearance, but cloudy for scrying to see and communicate with one's patron diety or spirit guides.
It's fun to do solo, and it's also fun to do it with other people, so long as none of them are too easily frightened. Don't use it to scare people! Ask for the protection and assistance of your guardian Angels, before you begin, and remember to get grounded, and stay grounded. If you can manage to get into the Witness state, so much the better!
To play the game, you need a dark room, a lit candle and a mirror. Preferably a wall mirror, so you do not have to hold it. By light of a single candle that's placed somewhere behind you or well off to one side, in a very dark room, gaze into a mirror. Look into your own eyes, or focus on the third eye spot between your eyebrows, on your forehead. Because of the light being very dim, you'll find that your eyes keep going out of focus. Let them. Avoid blinking to refocus your eyes, because it is the soft focus that will reveal the faces. When your eyes go out of focus, don't try to blink to clear them, let them go out of focus, but keep looking.
When your eyes go out of focus, your Third Eye will kick in, and it will start to show you other faces. Other aspects of yourself, past lives, faces from the collective, aliens, faeries, people of other races and other times, all kinds of faces. Some of them may be faces of old Gods, like Hecate or Thor. Some of them may be your Divine Beloved showing up to say hello. Often with people who are just doing this for the first time, the faces will flash by so quickly that you can't see them completely. Sometimes a face will linger so you can get a good look at it. I have seen a grey alien in my mirror, so steady and clear that I could turn my head and see the sides of it's head, and examine the tiny wrinkles in the dove grey skin around its large black eyes.
Some of the faces will probably be very scary looking. This is to challenge you to give unconditional love to All That Is. The grey alien usually freaks people when they first see it, because it is so strange, so very alien and unemotional. The old God archetype of Hecate, for example often appears with one side of her face a skull, and the other a cat! Yet, Hecate is a Mother Goddess, of hearth, home and patron of childbirth. Benevolent. So don't get scared of the faces you see, no matter how horrific they are. Just pretend you're Stephen King, and you're looking for material for a good novel. As long as you stay grounded, the faces won't scare you. It's very important to do this exercise when you're grounded.
Again, it's very simple. A completely dark room, a mirror, like a bathroom mirror, if you can sit comfortably in front of it, or you can do it standing. One candle, not in front of you, but behind you or off to the side somewhere. The room should be dim enough so that you can just barely can make out your features. You can just barely see yourself as your eyes adjust to the light. Set the candle down, be grounded, relax, allow your eyes to go out of focus, and stare into the mirror.
If you focus on your Divine Beloved, it may show up so clearly that you can almost talk to it. Which is a very interesting experience, seeing the opposite gender version of yourself in your bathroom mirror. Let your eyes go out of focus, and just give unconditional love to all of these reflected images, and all the faces that come up. No matter how scary they may look, they can't hurt you. They're just showing up so you can love them.
By loving them, you reduce the separation and integrate them as part of your Self. Not in a bad way, simply in a way that we are taking the separate ego-mind, and we are bringing it down through the levels of the unconscious. At different levels of the unconscious, the past lives, and the archetypes, and the collective faces are available as information. As you move down through the collective, there will be more and more faces. And then finally, as you get closer to Unity, there will be fewer faces. They'll gradually reduce until you may see the same half dozen faces coming up again and again. Where before, you were seeing a thousand faces in an hour, or even more.
Eventually, you will vanish! Where your head used to be, there will be nothing, and you can see the wall behind it. This might freak you out the first time it happens, but it is very positive. The Buddha aspires to be nothingness.
This is perfectly normal. It's a good way to open and work on your Third Eye. All I have to caution you against is to be very grounded, and not to be afraid of what you see.
That is the challenge, to give unconditional love to All That IS, and accept it. The faces can't hurt you, but they're neat, they're fun to watch. Enjoy it! Blessings...