Iridian Bridge

A blinding light enveloped me. Swirling colours were everywhere as I could feel the world move around me. And when it dissipated, I found myself here...

Prismaria is a world in constant flux, as the light of sacred Lux eternally fights to keep the inky black Void Fog at bay. While Lux's magic of creation can bring forth new terrain from the nothingness of the fog, it can also transport material from other realities.
When land is transported across dimensions, a bright column of vibrant light shines forth at both ends, linking across realities in a great arc akin to a rainbow. Dubbed an Iridian Bridge by the people of Prismaria, the sighting of one is cause for much excitement as the map is redrawn. The brightness and intensity of the arc of light is directly proportional to the size of the terrain being transported, while frequency exponentially decreases as size and luminosity increases. Small and faint "rainbows" are frequent and can happen daily, while the largest and brightest spheres of terrain over a mile wide may occur only once or twice in an entire Age.
There is some debate over whether the Iridian bridges are swapping material between both ends or simply copying it from the far side. There is evidence to suggest material swapping is taking place, as the transported material arrives in Prismaria as a perfect sphere that completely replaces whatever was there before. Normally only the Void Fog is replaced after an Iridian Bridge, with small gaps being filled in by Lux's creation magic, but occasionally sections of preexisting terrain are replaced too.
But if material is being swapped between both ends rather than copied, is the Void Fog being transferred across? And if so, what are the implications for the worlds on the other side?

Type

Metaphysical, Astral