EM shield

The electromagnetic shield, commonly called , is an electromagnetic barrier created by generators deep within the Houses of the Sanctuary Network in order to protect the Sanctuaries against teleporters.

History
Teleportation from outside the boundary of this energy field to a destination anywhere within a Sanctuary would result in the unwanted teleporter's energy signature being rejected; they are rematerialized just outside the barrier and simultaneously thrown back from the shield, leaving them slightly disoriented. This was seen in the case of Druitt when he attempted it. Doing so from within the Sanctuary while the EM shield is up however, poses lethal danger as it incinerates the recipient at a molecular level. When a teleporter dematerializes, their energy signature is severely interfered, vaporizing them on the spot.