The world itself.

Planes, Dimensions and Time

In the Vesper Linder World, there aren't just Planes of Existence, but Dimensions and Time to travel through and experience as well.

Planes are basically mere copies of Dimensions. It depends on how far the Dimension has traveled, as per its rotation in the Multiverse and how 'close' the Dimesion is to the Material Dimesion or Plane.

Unlike our planet on Earth, rifts of the Multiverse move and exist all through Linderen. That means actual 'mini black holes ' actually move tbroughout the world like creatures would and do.

Linderen

Linderen is the known world of the PCs. Most have a picture of the world in their heads because of satellite magic, which may have differing points of view, but generally relays the same picture.

Half if not most matter is animate and intelligent.