Dwarven Trans-Portal

A transport mechanism created by the dwarves to instantly teleport from one location to another regardless of distance. The portals are rumored to still exist in lost dwarven strongholds and sacred temples.
The cost to build and power such a transport is prohibitive for mass production. However, the major weakness of the portal (which the dwarves were never able to solve) remains each portal's ability to transport to only one other portal, connected to each other at the time of their creation. The next link in the chain so to speak. Should the link be broken, then both portals are useless.