Nerra

Manual of the Planes, pg 311

Beyond every reflection there is said to lie a mirrored world, a place which may represent another parallel timeline or perhaps a connected realm elsewhere in the planes. In the space between these relections dwell beings known as the nerra, mirror-skinned beings who observe the world through windows of reflection. The glasslike bodies of the nerra can also be weaponized into deadly razor storms or crafter into elaborate shard weapons. On rare occasions, individual nerra may step from the space between mirrors to answer summons from Architects of Destruction , cleaving the battlefield before their masters reshape existence.