Eberron - Return of the Lich Queen
Xoriat the Realm of Madness is beyond description. Merely visiting the plane non-natives risk having their minds shattered at the sight of the chaos. Alien architecture and unspeakable inhabitants exist in the exanse of the highly morphic plane with no gravity and wild magic. Time there flows more quickly 1 minute equal to 1 hour on the Material Plane. The home of the Daelkyr the realm’s last coterminous phase was nearly disastorous for the world of Eberron. Decimating the Dhakaani Empire it was only through the efforts of the Gatekeepers who sealed off the dimensional portals and placed many dimensional seals on the plane to keep it away from ever becoming coterminous again.