The Twillight Void
As far as the young magi of Treverorum can discern, the Twillight Void is the stuff between the areas of the magic realm that they have visited so far.
As far as the magi can discern it is always possible to walk through a boundary or vestige into the void. This will cast one adrift. It is then possible to swin towards a destination.
It seems that the gift of second sight is vital in this endeavour.
Also knowledge of ones destination, either through an arcane connection, having been there before or similar, is paramount.
Without these ties to the destiantion travel may take months or even years,
In one instance it took the young magi a season to return from the magic realm to Mount Blanik.
As far as the magi can tell arcane connections do not function normally.
Vestiges and boundaries can be arcane connections to places in the magic realm or even the mundane realm. But nothing else can. Perhaps it is possible to create vestiges with magic that can serve as arcane connestions.
And perhaps Rego magic can help travel in the void.