Gate mages, described in the Mither Mages series by Orson Scott Card, are potent healers, tricksters, travelers, and linguists. They have some potential as damage dealers in that they can use gates to cut off body parts. Or create two gates so that an arrow can be sent back at the shooter. They can also be fairly hard to kill due to being able to escape and heal.
What they can do in the books makes them gods so they are fairly over powered.
Description from the Mither Mages Wiki
A Gatemage was arguably, along with a manmage, the most powerful of all Mither Mages. A servant of spacetime, a gatemage was able to create a portal, or "gate", that would transport a person or thing instantaneously between two points. Gates, in addition to being powerful means of travel and manipulation, would heal any wound when a person passes through.
Gatemages also had the power to create Great Gates, which were formed by weaving a dozen or more gates together and extending them from one world to another. The passage between worlds (Westil and Mittlegard) greatly strengthened any mage's power many fold. Thus, gatemages were extremely valuable to fellow mages in the quest for greater power. Were forced to be killed because Loki closed all the great gates and if a family could get there hands on one that could make a great gate they could destroy the other families.
How could one implement them (perhaps as a new class) in D&D 5e or Pathfinder? Pointers to past implementations are also welcome.