Using this ability, Gareth and Kay will be able project the image of any location into any mirror. It won't have to be a location they have seen himself, or even one which exists in reality. Then, they will be able to pull objects and beings from the image into their present location, or step into the mirror and travel into the image's location. They could also use this to communicate, by either slipping messages through or only putting their heads through the mirror. They could also use this ability to watch other locations and to spy.