Havard wrote: ↑
Sun Nov 10, 2019 9:04 pm
The Underdark is also becoming presented almost as a separate plane
This physically hurt to hear/read.
I personally have decided to treat the Feywild as an Alternate Prime Material Plane (I use the Planescape cosmology with additions and minor alterations). It is, specifically, an APMP where 'civilized' races did not naturally come to exist. The worlds of this APMP are primal and natural, unshaped by the hands of building races. These worlds are populated by fey, fey-touched, sylvan, and all manner of natural creatures, but lack anything along the lines of truly native elves, humans, orcs, goblins, etc. What humanoid races do exist are very unimpactful (muckdwellers, druidic lizardmen, sylvan centuars, etc).
Being an APMP means that its own cosmology can be different, but after a lot of thought, I have kind of decided to embrace the idea of parallel worlds. The Feywild is, at least in part, very 'closely' aligned to the 'standard' D&D Prime Material Plane (ie, the plane on which the worlds of Oerth, Toril, and Krynn are found). Because of the way APMPs work, I've long had a rule that 'close' planes are easier to travel between and are more likely to be similar to each other than 'distant' planes, so the Feywild being an 'unspoiled' version of the 'standard' PMP fit into my existing cosmology. Thus, in my view, it would have its own crystal spheres with their own phlogiston. Therefore, based on this view of the Feywild, one could spelljam between the various worlds and then use natural means to move from those different Feywild worlds to their normal counterparts. Of course, that would raise the question of how to do that and what one would find beyond those worlds. The first is easy to answer, but tricky to overcome for players: no civilization means no spelljammers, no helms, not boats, and not much in the way of magic items to begin with (fey are inherently magically and rarely use weapons, and few of the sylvan races dabble in metallurgy). The second is harder to answer. I've had an ongoing project to expand fae races, and I've definitely added races that would for sure be found in wildspace and maybe even the phlogiston, so I'd expect that anywhere you went there would be fey creatures.
For the Shadowfell, I just treat it as an alternative name for the Plane of Shadow. People across the planes continually underestimate the scope and breadth of the Plane of Shadow, and it has many names and descriptions (after all, shadows are ever-changing). The plane does have twisted, shadowy reflections of worlds...in fact, any place in existence where light exists, there are shadows, and thus a region in the Plane of Shadow that reflects it. But there exists much beyond those reflections that is home to the true Plane itself; think of it somewhat in terms of the Ethereal; those shadowy versions of places are the Border Shadow, touching on other planes, while the parts that don't reflect *any* places are the Deep Shadow, the actual pure plane itself.