The Mirror of Reality is a key item in Hell on Earth. It is able to teleport, allowing a user to travel between locations, or even whole planes of reality, sending the mirror with them. It can also be used as a trap to send someone somewhere, though the mirror will not be sent with them. It requires the Twelve Sacred Gemstones in order to function.
The mirror is used by staring at the mirror and thinking of a location. Hysterically enough, this means it can very easily be used on complete accident (this is how Josh Shape teleports to the world of Hoep). One doesn't need to know what a location looks like as long as they know its name, and vice versa.
The mirror is used as a trap by laying something behind it that is representative of the area or plane you want to send the victim to, such as an item or drawing. This isn't an effective trap, though, since the victim still has to look at the mirror intensely, and the trap is disarmed if the object is removed from behind the mirror.
The Mirror of Reality has an intricate, ornate frame with twelve slots, one for each of the Twelve Sacred Gemstones. The mirror section isn't made of glass, but is instead made of Mithril polished to the point of creating a clear reflection.
When someone is looking into the mirror, their reflection is normal. When the Twelve Sacred Gemstones are in the mirror, and someone looking at the mirror thinks of a location, their reflection will change as though they were at that location. When the mirror is trapped, the reflection shows the setting of the location the victim will be teleported to, and if they are visible, it will show them as if they were at the location.
Relevance to the story
Foster Forfant makes the Mirror of Reality with the intention of sending it with someone to the real world, where they will use it as a trap on Joseph. This works, but the agent sent with it is trapped in the real world after being unable to recover the mirror due to Josh Shape's interference.
Alongside this, the mirror can also used for PROTOCOL:EJ, which would allow Foster Forfant to turn the mirror into a device to remove Joseph from existence while still allowing the world of Hoep to exist. This is done using a special machine, potent magic, and the power of the Twelve Sacred Gemstones.