Arcadia(Plane)

Arcadia is the natural home of Fey. Yes, not the Feywild. Fuck you. It's the plane of Dreams, and in the Era Before Time in Nexus, the Fey of this plane claimed the shade of positive energy, what is now known as the Feywild, while the dragons, giants and the like fought over the Material plane and the mortals within. Not that their wars have ended.

Unsurprisingly, due to the extreme time periods involved, the Feywild and Arcadia are very close in a Planar sense. There are more portals between these planes than most others, to the degree that some people want to mark the Feywild as a transitional Plane to Arcadia.

Arcadian Gateway
The Arcadian Gateway is a separate plane from Arcadia proper, and was their grand effort to stay out of the various universal threats in the Astral Sea; Their way of keeping out Juggernauts, the Blood War, the Crusades, and so forth. The Plane itself is managed by a pair of Archfey called the Gate Keepers. Their job is very obvious, and if you must ask what the Gatekeepers of the Arcadian Gateway do... Just... Just go.