Planejammer Campaign Setting
There are a few points where the multiversal barriers are thin. Through these it is possible to travel from one alternate multiverse to another without suffering the trials of passing through the Far Realm.
One of these points is the planet Oerth in Greyspace. Oerth is a nexus point. It has five shadow selves – Oerth, Aerth, Yarth, Uerth and Earth. More than a thousand other worlds connect to one or more of these shadow selves. Among these connections, Oerth features most prominently, having the most direct and indirect connections to other alternates.
These parrallels differ in both their geographies and their physical laws. The five most easily accesed are Earth, Uerth, Yarth, Aerth, then Oerth. Each of these worlds exists in a different multiverse, and almost certainly is surrounded by a different arrangement of planes. The levels of magic, psionic energy, technology and more vary considerably from Oerth’s baseline.
For dimension travelers starting in the Great Wheel Oerth is the safest starting point when attempting to reach alien cosmologies such as the Dragonstar multiverse or our own modern day world. Perhaps this explains the ease with which Murlynd has been able to travel back and forth so much over the decades…