Dreamspace

From Secrets of Sarlona:

Planar gateways that once linked Eberron and Dal Quor, the Region of Dreams, were sundered during the cataclysmic wars that destroyed Xen’drik and shattered the giant civilization. Since then, Dal Quor has been forever distant, and no stable manifest zones to Dal Quor exist anywhere on Eberron.
However, Dal Quor and Eberron remained inextricably linked by the state of dreaming—the process by which mortal minds travel to the Region of Dreams, and the subtle gateway through which the quori first began their conquest of Sarlona some fifteen centuries past.
Discovered short years ago and still known only to few, the dreamspace is an effect that appears related to this spiritual connection between planes, but one that as yet has no explanation. It appears as a kind of ripple of arcane and psionic energy—a border of sorts between the mortal world and the world of dreams. Where dream and reality touch, a vortex of shifting light and sound unfolds. The world as seen through the dreamspace appears as it truly is, but its colors are alternately muted and intense. Creatures who can see into the dreamspace observe shifting auras that surround living creatures and psionic or magic objects alike. Light and shadow bleed into each other, and an echo of unintelligible voices twists through the hiss of a never-ending wind.
Though powered in some way by the energy of Dal Quor, the dreamspace is a Material Plane effect. It is not simply a manifestation of the Region of Dreams, nor is it connected to the dreamscapes that ring Dal Quor, which are employed by the quori mindhunters (see Magic of Eberron) and others who seek to hunt and destroy the quori on their home plane.

In the years since the end of the Last War, the fall of the Tower of the Twelve, and the havok that an Overlord caused in a few weeks of escape from it's prison, the quori have made use of the dreamspace in new ways -- using it in ways that allow the quori masterminds to leverage the power of planes like the Feywild to act as a sort of bridge between Dal Quor and the mortal realm.
This has proven to be especially effective in the case of the Feywild, thanks to the mutable and playful nature of the feywild itself. Some domains with in the feywild make themselves especially good conduits for dreamspace energy -- and the domain of the Autumn Queen is one such good conduit.
Quori Wajda has been using it's inspired agents as well as quoribound and quoribred monsters to exert some control over The Amber Forest and use it to extend control over the mortal realm that is associated with it. This is done by creating a Hanbalani Altas in both places and binding the two together with dreamspace energy.