Mirrors are the ancient devices which allow travel across dimensions, and are supposedly the means humans, sssrra and uleem first came to Kalyr. It’s widely believed that all such devices were destroyed centuries ago, and the knowledge to build them long forgotten, but nobody really knows for sure.
From surviving descriptions, the heart of the mirror resembles a doorway. When the mirror is inactive, it appears as a heavily-constructed doorway covered in heavy cables linking it to control panels and power sources. When activated, a shimmering plane fills the doorway. Normal senses can’t penetrate the shimmering plane, but a skilled psionic strong in the Way of Vision can detect what lies on the other side of the mirror.
The mirror ‘focuses’ on a specific point on another world, where it will appear as a misty shimmering not unlike that visible in the mirror on Kalyr. The operator can move the focus point, although it needs a psionic to steer it. Anything that intersects the shimmering passes through, and will be physically transported between Kalyr and the other dimension.
The principles behind the mirrors have never been fully understood, and there are all sorts of complications that cause interference patterns and echoes. Quite often people and creatures passing through the mirror to Kalyr don’t appear though the mirror itself, but will be displaced a considerable distance away.