Magic portals to distant locations are uncommon in magic settings, but the concept is a well known one. They seem to be heavily utilized in Faerun (Forgotten Realms), and I will talk a bit about that implementation.
Magic portals in Faerun require a password to activate (like the original magic wands) and everything and everyone inside the magic circle are transported to a linked circle. There seems to be a 1:1 relationship between circles and while it is not specified or said, there is probably a limit to the number of times a circle can be activated (daily or weekly, perhaps). There is also a suggestion that the linking can be ‘re-tuned’ – so perhaps you could retrain the destination if you had the right information.
Magic portals could be more complex. I designed the portal system in my current campaign to work so that the outer ring could be directed to a particular ‘address’ and you could spend the daily charge attempting to go there, but portals can be locked or set to only accept visitors during a narrowly specified time. Most portals also spin the outer ring randomly after their use, so the address last used is lost.
Another tact for a magic portal is that of an enduring interconnecting wormhole between two places. The wormhole might be open constantly or it might open briefly under the right astrological circumstances. How it appears could differ – an inky, shifting blackness when a door is opened, or perhaps touching or using something causes that person to disappear and reappear at the destination. These types of places would be as much about one’s knowledge of them as one’s ability to reach them, being perhaps part of the powerful remains of an ancient civilization.
One could also introduce a ‘Terminator’ factor to the travel and prevent metal and inorganic materials from making the trip. This would be especially disagreeable to most parties – they’d probably rather walk the length of a continent rather than forgo the use of their treasured magic items.
More rarely, magic portals are used as traps, typically transporting the ‘victim’ deeper into a dungeon, but they could just as easily send them to a different plane of existence.
I generally prefer to go without magic portals or, if I do use them, I will go with the rare remnant of an dead civilization. The ability for factions to create portals would be a primary weapon of war, allowing troops to ignore walls and distance.
I know that high-magic settings demand such things, but I still chafe at the difference between how they are used in the game versus how I believe that they would actually be utilized – as a tool of war. Wow, sounds like a good idea for a campaign high-level over-arching plot…
This article is a part of a series on how to customize your campaign without really doing too much laborious work. Each article outlines an idea or a series of related ideas or concepts, each of which when fully considered and blended into your campaign will help to make it unique and more fully realized.