Portals & Teleporters FAQ

Here are some rules for how they operate, their limits, and interactions.

Portals

Can lead anywhere and any distance, at least in theory. Including other worlds/dimensions.
Must be against a surface, not in mid-air. Often built into a wall as a permanent feature that can be activated and deactivated with some magic knowledge.
They require familiarity of where you want it to lead to, unless there is a permanent portal structure built on the other end. (Like using teleportation circles)
They must also be maintained while open. By a single wizard for a normal human sized portal, or by several wizards for a larger portal. But people on either side of the portal can maintain it.
Sound does not travel through the open portal, but light does, though everything looks out of focus or blurry as the light gets scattered through it.
Temperature differentials don’t matter, though if there is enough light travelling through, it can cause the area around a portal to get hot.
Pressure differentials don’t matter. So a portal from sea-level to a mountain top won’t cause a rush of air.
Solids are the only types of matter that can travel through the portal. Liquids and gasses need to be fully enclosed to take through. This prevents air and water from flowing through the portal, such as if you opened a portal to the vacuum of space or the bottom of the ocean. This also means many magical things can move through, such as elementals, illusions, or conjured objects.
Repeated travel through portals can cause a condition called portal rash, where the skin becomes irritated from the moisture on your skin not travelling through to the other side of the portal, causing dryness. It is also why many people prefer to close their eyes while travelling through the portal to avoid eye irritation.
If something causes the portal to end while someone is travelling through, they could end up anywhere. Another location, another world, or even (if you are comfortable with it) another time.
If two people or objects try to move through from opposite ends at the same time, they will bump into each other and cannot completely move through. They will both be at risk if something causes the portal to close suddenly.
Pocket dimensions and extra-dimensional spaces should not be brought through a portal. They cause a random chance for the portal to close itself suddenly.

Teleportation

Target and destination must be line-of-sight, unless using a teleportation circle or similar device. But even then, teleportation is limited to within the same world/dimension.
You can try to teleport to an area you can’t see but there is a high chance of failure. Resulting in possible death or arriving at the wrong location.
Leaving from a teleportation circle removes the chase of death for teleporting somewhere you can’t see. Arriving at a teleportation circle removes the chance of arriving at the wrong location. So using a circle at either end will result in safe travel without line of sight.
Arriving at a circle where someone is already standing will cause you to not teleport at all if there isn’t enough room for you. This means you can block a teleportation circle by covering it in crates and barrels, or by crowding it with people. So you don’t have to destroy the circle to disable it.
Unless using two circles, teleportation can be blocked by the materials between the target and the destination. It will be blocked by 20 feet of dirt or wood, 10 feet of stone, 2 foot of metal, or 6 inches of lead. You will still teleport as close to the destination as possible. Arriving at the point where a straight line between the source and destination intersect with one of those blocking materials. This means that teleportation circles are often built on top of towers to make it easier to avoid those materials.
Unlike portals, teleportation can also be magically blocked through anti-magic fields and magical effects. Some unusual places are permanently resistant to teleportation because of a magic effect or aura that permeates the area, including many elemental planes.