EM shield

The electromagnetic shield, commonly called EM shield, is an electromagnetic barrier created by generators deep within the houses of the Sanctuary Network in order to protect the sanctuaries against teleporters. Teleportation from outside the boundaries of this energy field into anywhere within the Network would result in the unwanted teleporter materializing back and then getting thrown back by the shield, leaving them slightly disoriented. Doing so from within the Sanctuary while the EM shield is up poses a greater danger, incinerating the recipient at a molecular level as their dematerialization is severely interfered and vaporizing them on the spot.

The system was installed by Dr. Helen Magnus primarily to protect her network from teleporters, but later proved vital in defending against the Cabal's super soldiers, who had also acquired the ability to teleport.