Zigguraxus

Zigguraxus was the home plane of the Untheric pantheon, manifesting as a vast mountain with its peak eternally covered in mist under a starry night.

Background
When the pantheon was dissolved in 1358 DR after the deaths of Gilgeam and Ramman, the plane disappeared from Toril's cosmology.

In 1487 DR, the returned god Enlil rebuilt the plane for some purpose.