Ard Gaeth, called Gates of the Worlds or High Doors, are large scale portals that allow entire populations to move across the multiverse. Before the Conjunction of the Spheres, the Aen Elle controlled one or more such Gates, which they used to leave the Continent and conquer other worlds. Unfortunately for them, they lost control over the Gates after the cataclysm, which forced them to begin the Elder Blood genetic program - according to Ithlinne's Prophecy, its result, the Swallow or her...
