Powerful mages (Master and Adept class) can construct Gates for quick transportation from one place to another. Both people and items can be moved through a Gate. The Gate bends space connecting one spot to another, making it possible to cross a continent with a single step.
The problem with Gating is that it takes a great deal of focus and concentration, making it impossible for a mage to regulate power coming in from an outside source. Therefore, the mage is limited to only his or her personal energy reserves. Gates also take a tremendous amount of power, draining the mage who casts it, and leaving him or her helpless on the other side.
The sole exception to this rule was when Tylendel used Vanyel to supply Gate energy. Their lifebond connected them at such a deep level, that in many ways Vanyel's energy was Tylendel's, and vice versa. Without the lifebond, this could not have been accomplished.
Building a Gate Edit
When building a Gate, the mage begins with an existing doorway. It is easier if the frame has been used for a Gate previously. He begins weaving the energy from the doorway, sending tendrils out seeking the destination point. He must clearly visualize the exact location for the terminus. This is another reason a Gate can be built by only a single mage. No two people visualize the same location in precisely the same way. This is also the most dangerous point in the spell, as the Gate can drain a mage all the way to death if he or she isn't careful.
The terminus of a gate also needs to be a doorway of some kind, to frame the spell. Once the spell tendrils latch onto the termination point, the Gate flashes into existence with a "silent explosion of light." (Magic's Pawn)
As a Gate continues to drain the mage who cast it as long as it's open, they aren't usually left open long enough to doing anything more fancy than move from point A to point B. However, a talented mage can re-route a Gate, moving the terminus to another point. Savil does this in Magic's Pawn when she moves Tylendel's Gate terminus from the ruins outside of Haven to the Grove temple door. Vanyel does something similar in the Mage Storms trilogy when he hijacks a Gate to bring Elspeth and Firesong to the Forest of Sorrows, instead of their intended destination in Haven.
The Adept Mages in ages past knew quite a lot more about Gates. Much of their knowledge was lost in the Mage Wars, though some remnants survived. Most notably, Clan k'Leshya preserved the knowledge of building half-Gates, which allowed two mages to work together to build the Gate. With this technique, one mage was stationed at each Gate terminus with enough knowledge of the opposite terminus to Gate there. Then each begins the Gate spell, meeting in the middle. One or both can hold the Gate, preventing a massive energy drain to either mage. k'Leshya taught this technique to the mages of Clan k'Sheyna, and used it to help k'Sheyna reunite their Clan at their new Vale site.
Gates and warfare Edit
While at first glance, Gates might seem tremendously useful in war, the need for the mage building it to be personally familiar with the terminus point, severely limits their utility. An invading army can only Gate behind their own lines. A defending army can Gate behind enemy lines, as they are familiar with the terrain, but they can only use that trick a few times if the invaders also have mages. Eventually, the invading force will set their mages to watch for the distinctive signature of Gate energies and blast the Gate as it forms. Given how closely tied the mage is to his Gate, and how vulnerable he is while building one, blasting a forming Gate generally has the effect of not only disrupting the spell, but also killing he mage on the other end.
Master Gates Edit
Before the Mage Wars, a handful of Adepts, including Urtho, built permanent Gates, called Master Gates. These were linked together in a network. A mage keyed into the Gates could use them to travel from any Gate to any other on the network without the huge power expenditure of a normal Gate. The simple activation spell was well within the capabilities of even the lowliest apprentice. Urtho also knew how to key a Gate so that it could be used by non-mages to go to a preset destination. This was how he evacuated his people just ahead of the Cataclysm, through ten preset Gates.
When used as a Gate terminus for a normal Gate by a mage keyed into the network, the temporary Gate again took only a fraction of power to build, leaving the mage able to cast other spells after traveling through.
One of these Master Gates is located in the Dhorisha Plains, in the remains of Urtho's Tower. It was one of the Gates used to evacuate the Kaled'a'in just before the Cataclysm. Another Master Gate, probably dating to this same period, is under the ruins at the edge of k'Sheyna territory, where Treyvan and Hydona built their nest.