The Breach is the name given for the division between the Shadowfell and the Material World. As the Shadowfell’s influence grows, the line moves farther and farther south. The effect this has on the material world — the ever-advancing wall of death and decay — is also known as the Blight.
The exact nature of the Breach is not certain. Leading theories suggest that the Shadowfell has somehow been superimposed on top of the Material World within the Breach’s confines. This is supported by the fact that the terrain and even man-made structures within the Breach look familiar — it still looks like Amnos, albeit a drab, decaying version of it. Forts, villages, and other structures exist as crumbling shadows of their “real” counterparts.The most peculiar thing about the Breach is that it is not quite visible. If one stands on the south side of the Breach and looks north, nothing seems out of the ordinary, except for perhaps a slight shimmer in the air if viewed on a sunny day. However, entry into the Breach could not be more obvious when one takes the final step from the Material World into the Shadowfell. The landscape shifts suddenly to a sunless, gray echo of the Material World. Stranger still is the fact that, if one then looks southward, the Blight continues on to the horizon as if the Material World was never there to begin with.