Creating a Portal
The creation of portals is one of the principle foci of wizardry. Whereas other spellcasters have some ability to create portals to the realms with their magic is most strongly attuned (the Astral for seers, the Maelstrom for sorcerers, the Nether or the Pit for warlocks, the Prime for theurges, etc.), wizards have refined a unique method of portal creation that is agnostic to the destination.
Regardless of the magic involved, the key to erecting any portal is proper attunement. The process itself involves joining the present location to a separate, distant location. This is simple enough for a reasonably adept spellcaster. However, controlling the end point of the gateway requires an object that is strongly attuned to the desired destination. This object is commonly referred to as a conduit.
A conduit may be any item that has spent a great deal of time in a single area. The less this item has been disturbed, the better. Thus, a piece of stone from a castle wall or a flower from a garden often serve as excellent conduits for reaching those locations. Of course, since the item must be taken from its resting place to serve as a conduit, they tend to lose their attunement rapidly.
There are substances that retain their attunement long after they have been moved from their original location, however. A magnetic mineral known as lodestone, for example, can be buried at a desired destination, whereupon it becomes attuned rapidly and retains its attunement almost indefinitely.
Symmet weed is another popular, though less permanent, conduit. This plant has the unique property of growing in perfectly symmetrical pairs. If one half of a pair is removed, it remains attuned to the other half regardless of its location. In this way, portals can be created without any prior attunement by sending matched pairs of symmet weed to the desired endpoints.
Even people can act as conduits for places they frequent, such as their homes. Because people are less stationary, however, their attunement is weak, and so portals using people as conduits tend to be skewed.
Without a proper conduit, the end point of a gateway may vary wildly or the gateway may fail to precipitate at all.
It is possible to erect a permanent portal adjoining two locations. Doing so is a painstaking process that involves cultivating enough conduit material (usually lodestone) at both locations over a period of months. The material is then moved to opposite ends and constructed into doorways. Wizards at each end must then perform coordinated rituals to precipitate the portal itself. Doing so during particular celestial or lunar phases helps ensure that the resulting portal does not break down over time.
Risks of Portal Travel
Portals are notoriously fickle. Weak attunement can result in a skewed destination, causing travelers to arrive miles off their mark. In addition, local magical phenomena can interfere; a portal created in a verdant druid's grove, for example, could end at the right location but deposit travelers in the Near Prime instead. Even celestial events can distort otherwise safe and well-established portals.
Thankfully, a portal that ends in solid matter simply fails to precipitate. However, this hasn't stopped reckless travelers from unexpectedly ending up high in the air, underwater, underground, or in similarly hazardous environments, such as volcanoes. This is to say nothing of arriving in the middle of areas infested with hostile monsters or on private premises. More than one portal traveler has had to explain themselves when they inadvertently intruded on a privy, a bed chamber, or a well-guarded treasure vault.