Xoriat

Xoriat, The Realm of Madness is one of the Planes of Eberron.

Xoriat consists of many stacks of translucent layers, an apparently infinite amount of planes stacked upon one another. Its inhabitants exist on multiple layers simultaneously. Massive, drifting entities too large to notice visitors to the plane; free-floating rivers of milk-white liquid; rains of blue globes falling from unseen heights, only to burst and release horse-sized ticks when they strike another object -- these are typical sights on Xoriat. Gelatinous worms wriggle from layer to layer, wending through tentacled vegetation encrusted with orange moss, all suspended above an amoebic sea. Time on the plane of Xoriat flows differently from time on Eberron. One minute in the Realm of Madness is equal to one hour on the Material Plane.

Since the end of the Daelkyr War, Xoriat has been kept away from Eberron by the magics of The Gatekeepers, taught to them by the ancient dragon Vvaraak. However, the magics of the gates have been weakening over the last thousands of years, and it is presumed that Xoriat will return.