Magic portals link many places across Toril. A portal is simply a permanent teleportation effect that safely whisks its user to a predetermined place. Most portals lead from one place on Toril to another, but a few lead to other planes or other celestial bodies in the skies of Toril.

Qualities of Portals

Hundreds of archmages, high priests, secret circles, monstrous races, and dark cabals had a hand in creating the multitude of hidden doorways riddling Faerûn. Magic of this sort is unusually durable, and often survives for centuries - or millennia after its creators have vanished into history or lost any use for their handiwork. Accordingly, the workings of portals are mysterious and unpredictable. Each one is built for a reason, but all too often these reasons are lost when the creator passes into history or obscurity.
Portals share some common features and qualities. All portals are two-dimensional areas, usually a circle with a radius of up to 15 feet, but sometimes square, rectangular, or another shape. The portal itself is intangible and invisible.
Portals often come in pairs or networks, A single portal is a one-way trip. There must be a matching portal at the destination to return. Some portals are attuned to several potential destinations, each equipped with a matching portal, but most are simply two-way doors between one point and another far distant. Once created, a portal cannot be moved.

An archway or frame of some kind usually marks a portal location so it can be found when needed and so that creatures don't blunder into it accidentally. Detect magic can reveal a portal's magical aura. If the portal is currently functioning (ready to transport creatures), it has a strong aura. If the portal is not currently able to transport creatures (usually because it has a limited number of uses, and they are currently exhausted), it has a weak aura. Strong or weak, a portal radiates transmutation magic.
The analyse portal spell can reveal even more about a portal.

Creatures who touch or pass through the area of the portal are instantly teleported to the locale the portal's builder has specified. (The teleportation effect is similar to teleport without error cast by a 17th-level caster, except that interplanar travel is possible.) It is not possible to poke one's head through a portal to see what's on the other side. A portal can only transport creatures that can fit through the portal's physical dimensions.
If a solid object blocks the destination, the portal does not function. Creatures, however, do not block portals. If a creature already occupies the area where a portal leads, the user is instead transported to a suitable location as close as possible to the original destination. A suitable location has a surface strong enough to support the user and enough space to hold the user.
Unattended objects cannot pass though a portal. For example, a character can carry any number or arrows through a portal, but he cannot fire an arrow through a portal. An unattended object that hits a portal simply bounces off.
Unless the builder has preset some limit, any number of creatures can pass through a portal each round, A creature using a portal can take along up to 850 pounds of gear. In this case, gear is anything a creature carries or touches. If two or more creatures touch the same piece of equipment, it counts against both creatures' weight limits.

Portal builders often restrict access to their creations by setting conditions for their use. Special conditions for triggering a portal can be based on the possession of a portal key, the creature's name, identity, or alignment, but otherwise must be based on observable actions or qualities. Intangibles such as level, class, Hit Dice, or hit points don't qualify.
A keyed portal remains active for 1 full round. Any creature who touches the activated portal in the same round also can use the portal, even if such creatures don't have a key themselves.
Many portal keys are rare and unusual objects that the creature using the portal must carry. Some portals are keyed to work only at a particular time, such as sunrise, sunset, the full moon, or midnight. Spells can serve as portal keys, as can the channeling of positive or negative energy. When the portal is the target of the specified spell or within the spell's area or touched by its effect, the spell is absorbed and the portal is activated. Any form of the spell works to activate the portal, including spell-like effects of creatures or magic items and spells from scrolls.

A portal cannot be destroyed by physical means or by spell effects that destroy objects (such as disintegrate), A successful targeted dispel magic (DC 27) causes a portal to become nonfunctional for 1d4 rounds. Mordenkainen's disjunction destroys a portal unless it makes a Will save (a portal's Will save bonus is +10). The spell gate seal (described later in this chapter) locks a portal and prevents its operation.

Unusual Portals

Things are never certain in the many lands of Faerûn, and portals are not always entirely reliable. Portal-makers have created through design or mischance portals with many insidious and dangerous characteristics.

These portals can only be activated at random times. They may or may not require a key for activation when they are working. A fairly common random pattern is a portal that works until 1d6+6 creatures use it, then shuts down for 1d6 days. Other patterns are possible.

These portals are hazardous in the extreme for those who are unfamiliar with their quirks. Creatures using these portals are transported to any one of several preset locations. The destination sequence may follow a set pattern or may be random. Some variable portals have keys that allow users to choose a specific destination served by the portal. Others function by transporting users to a default location - an inescapable dungeon, the innards of a volcano, or some particularly hostile outer plane unless the user presents the proper key.

These portals transport only the creatures that use them, not the creatures' clothing and equipment. Such portals are often used defensively to render intruders vulnerable after they use the portals. A rare and more difficult variation on this type of portal transports creatures to one area and their equipment to another.

The other types of unusual portals are generally created through careful effort by their makers. Malfunctioning portals, on the other hand, are almost always unintended.
Over the centuries, prodigious forces have swept over Toril, profoundly affecting magic. Because of decades (or centuries or millennia) of magical wear and tear or the strength of the cataclysmic forces to which they have been exposed many ancient dweomers have gone slowly awry. portals are no exception.
A malfunctioning portal is usually at least one hundred years old, but many are far older. Using one can have many different results. Roll once on the Portal Malfunction table each time a malfunctioning portal is activated. If such a portal functions continuously, the effect indicated lasts 1d10 rounds, and anyone using the portal during that time is subject to that effect.

Portal Malfunction

d%	Effect
01-05	The portal does not function, but draws magical power from the user in an attempt to power itself. The user is affected as though struck by a targeted dispel effect of a greater dispelling spell cast at 17th level.
06-10	The portal does not function, but draws magical power from the user's items in an attempt to power itself. A random number of items (1d10) are struck by an effect similar to a targeted greater dispelling cast at 17th level. Use Table 10-1: Items Affected by Magical Attacks, in the Player's Handbook to determine which items are affected. Successful dispelling suppresses permanent magic items for Id4 rounds. Charged or limited-use items lose 1d4 charges or uses as if they had been used to no effect and are suppressed for the same number of rounds (if still magical).
11-20	The portal does not function. The user is hurled away as though struck by the violent thrust of a telekinesis spell cast at 17th level. The user is entitled to a Will save (DC 17) to negate the effect and takes 1d6 points of damage if hurled against a solid surface.
21-25	The portal docs not function. Instead, a wave of negative (50%) or positive energy (50%) emanates from the portal in a 30-foot radius. Negative energy acts just like an inflict serious wounds spell cast at 17th level (3d8+15 points of damage, Will half DC 14). Positive energy acts just like a cure serious wounds spell cast at 17th level.
26-40	The portal functions, but it sends the user to the wrong destination. To determine where the user ends up, use the table in the teleport spell description (Chapter 11 of the Player's Handbook) and roll 1d20+80 as on the "false destination" line.
41-50	Nothing happens. The portal does not function.
51-100	The portal functions normally.

Building a Portal

Any character can build a portal if she knows the Create Portal feat and either the teleport, teleport without error, teleportation circle, or gate spell. The portal can lead to any locale the builder has personally visited at least once. The portal fails if the builder chooses a destination that cannot safely hold her (such as inside a solid object or into thin air). The portal also fails if the destination is a locale where astral travel is blocked (see the teleport spell description).
Base Cost: The builder must spend 50,000 gp on raw materials to create a single, continuously active one-way portal covering an area up to 10 feet in radius (about 500 square feet). The market value of a portal is twice its cost in raw materials. Crafting a portal requires one day for each 1,000 gp in its market price, and 1/25 of the market price in XP (one hundred days and 4,000 XP for the base portal. The builder can create a second portal at the destination point, making a two-way portal, for half price (25,000 gp, fifty days, 2,000 XP).
Larger and Smaller Portals: A portal can be crafted as small as 1 square foot (about a 6-inch radius), but this does not reduce the cost. The smallest portal usable by a Medium-size creature is 12 square feet (roughly a 2-foot radius). Small creatures can use portals as small as 7 square feet (an 18-inch radius), and Tiny creatures can pass through portals of 2 square feet (a 10-inch radius), Diminutive and Fine creatures are the only beings who can pass through portals of 1 square foot. Larger portals add 100% to the base cost for each extra 300 square feet of area or fraction of 300 square feet. Large and Huge creatures can pass through a standard portal, but Gargantuan and Colossal creatures generally need double- or triple-sized portals.
Special Properties: Some special properties, add significantly to the cost of creating a portal.
Keyed Portals: Keyed portal may be created at no extra cost. The key must be designated during the creation of the device and cannot be changed after that.
Random Portals: Random portals may be created at no extra cost. The conditions must be designated during the creation of the portal and cannot be later changed.
Variable Portals: Variable portals add 25% to the base price per extra destination after the first included in the device. For example, a continuously active portal with two variable destinations costs 62,500 gp to make. A continuously active portal with three variable destinations costs 75,000 gp to make.
Creature-Only Portals: Creature-only portals cost twice as much to make as standard portals. If the portal sends intruders' belongings to some place different from the users' destination, it is considered a variable portal with one extra destination.
Limited Use: The prices and construction times noted above are for portals that operate constantly, transporting anyone who passes through them at any time. If the portal can be used only four times per day or less, the base costs are reduced.
The materials and XF cost of a limited-use portal are based on the number of uses available. The materials cost is 10,000 gp × a portal's uses per day, and the experience point cost is 800 XP × a portal's uses per day. (The second portal in a two-way pair costs half this amount.) The market value is twice the materials cost. The construction time is one day per 1,000 gp of market value.
A portal usable five times per day or more is just as expensive as a continuously active portal. portals usable less than once per day can be created by using the appropriate fraction. For example, a portal usable once per four days effectively has 1/4 a use per day, costs 2,500 gp in materials, and 200 XP. The minimum cost of a limited-use portal is 1,000 gp and 80 XP for a portal usable once per ten days. (The portal builder can choose to have a portal operate even less often - once a year, for instance - but this does not reduce the cost or XP expenditure any further.)
Each activation of a limited-use portal lasts 1 round. Once activated, a limited-use portal can transport as many creatures as can touch it that round.

You have learned the ancient craft of creating a portal, a permanent magic device that that instantaneously transports those who know its secrets from one locale to another. Faerûn is riddled with portals.

Prerequisite: Craft Wondrous Item.
Benefit: You can create any portal whose prerequisites you meet. Crafting a portal takes one day for each 1,000 gp in its base price. To craft a portal, you must spend 1/25 of its base price in XP and use up raw materials costing half of this base price. See Chapter 2: Magic for details of portal creation.
Some portals incur extra costs in material components or XP as noted in their descriptions. These costs are in addition to those derived from the portal's base price.