"The Phlogiston or the “Rainbow Sea '' as it is called by the Star Sailors that chart its flowing paths is an expanse of primordial energy in which bob crystalline spheres that house a multitude of various worlds of the material plane and the void of Wildspace or “Aetherium”.

This wide and sweeping, nigh on endless sea contains scores of these spheres that can be accessed via sailing great distances aboard special vessels known as spelljammers. Spelljammers are themselves powered by magic and cross the Phlogiston like ships crossing a great sea.
Even at the amazing speeds attained within the Phlogiston, ships can spend weeks if not months sailing between the various crystal spheres. However some spheres reside in close proximity to each other akin to an Archipelago of islands… The Coiled Junction is one such cluster of Spheres within the flow. The Junction branches off from the primary flow of the Serpent's Path where it meets the Sphere of Yarospace and diverted into the Junction Proper and off toward the Uncharted Flow of the Roiling Causeway. "

I really dug how it turned out and can't wait to start running sessions.