Reality Shift

When many sufficiently powerful dreams occur simultaneously or in rapid succession, reality can become unstable and breakdown, forming a new Region in the process.

Manifestation

Stage I: Destabilization has very few indicators. The Office of the Dream Keeper will detect an anomaly in the area that is destabilizing.
A telltale sign that destabilization has occurred is when two or more people "share" a dream to the point that they can interact with one another in it.
Stage II: Fog is just as it sounds. The unstable area is enveloped in a moderate to highly dense fog.
Stage III: Dissolution and Reformation manifests as a shockwave that spreads outward, dissolving everything it contacts. A new Region forms in the wake of the shockwave shortly thereafter.

Localization

Areas affected are usually constrained to city-sized areas. It is rare that a small town or village will undergo a reality shift.