Dimensional Drift

The dimensional drift is the space inhabited by demons, is takes immense amount of power to break through, and up until the war of the realms, Filgrim the Pilgrim was the only demon to ever break through, and even he could only do it for short amounts of time, sometimes. But from the realms, there are dimensional bridges linking them together, but as a demon, you cannot get out of the drift from the inside. A dimensional drift is the space between a dimension and Arth, usually the people who can break through it are hostile, and can be a major problem for the realm they end up in, dimensional drifts were the reason all of Arth died during Finem Ludum, the gummepugits came from dimensional drifts, they ended up not being too much of a problem because of Vigil and Wakers amazing leadership, but you get the idea.