Oh, and to give everyone an idea of where we will be at when the story begins, our characters will all be gathering at Hub City, named so because it is the largest hub for interplanar travel. It's a floating city (I'm using Cloud City from Star Wars for visual references) that sits in a void between planes, encased in a bubble that gives it an artificial atmosphere and simulated a day and night cycle. Usually, people will first depart from their original plane, arrive at Hub City, and then depart to their destination plane. The Hub City Transportation Authority monitors interplanar travel to avoid collisions between various people jumping back and forth. Basically, the Authority has thousands of Seers who can sense incoming and outgoing travelers and can pinpoint exact locations for magical portals to open to avoid collisions, and then use their minds to move portals to those locations. So, because of that, Arcane runes or incantations used to open the portals when going through Hub City don't specify an exact location, only one of the many Port Zones, and then let the Seers guide their incoming portals to an exact location within the specified Zone. The same is done when exiting Hub City, using a small, predefined geographical radius if no participating Port Zones are at the destination area.