Xoriat

In the role-playing game Dungeons & Dragons, Xoriat is a fictional plane of existence set on the world of Eberron.

Xoriat, the Realm of Madness
Beyond words or comprehension, Xoriat is aptly called the Realm of Madness. Not only do its alien geometry and unspeakable inhabitants seem like the product of a madman's nightmare, but any who visit Xoriat risk finding their minds shattered by the experience.

Xoriat has been likened to a stack of translucent parchment, an apparently infinite connection of layers and dimensions. 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 -- such are the madness-inducing features of Xoriat. Gelatinous worms wriggle from layer to layer, wending through tentacled vegetation encrusted with orange moss, all suspended above an amoebic sea. Over this mad realm the daelkyr are absolute masters.

Xoriat's last period of being coterminous with the Material Plane was a disastrous period of warfare. Over seven thousand years ago, Xoriat became coterminous and the daelkyr sent their minions into Khorvaire to conquer it. Before the orc and hobgoblin druids known as the Gatekeepers managed to end the planes' alignment, the mind flayers and lesser minions of the daelkyr had decimated the hobgoblin empire of Dhakaan. The Gatekeepers' magic was less cataclysmic than the giants' attempt to close the connection to Dal Quor, however; Xoriat moved quickly out of alignment but is sure to return one day