From publisher blurb:
Aden is a vast and diverse world, but it is only one of many worlds that exist within the universe. There are other realms that can scarcely be imagined, ones that can only be visited with the most powerful magic, and that contain both wonders and horrors that can scarcely be believed even by those who witness them. Those that are closest to Aden, metaphysically speaking, are known as the Near Planes.
This gazette includes descriptions of some of the most commonly accessible planes in the cosmology of Aden, including the Elemental Planes of Air, Earth, Fire, and Water; the deadly realm of Arcadia, home of the fey; and the enigmatic Jhundata, a crawling realm currently closely linked to the nation of Kyan. Included is a new Edge, Student of the Planes!