1 plane below astlan?

Ahh, very good question.

Of course, to be fair, above, below and beside are rather vague and imprecise terms when it comes to planes.

In fact, that answer which, I think was me talking, doesn’t makes a lot of sense in reference to what those appendix things say.

However, it actually makes perfect sense to me.

As to what the meat in the Astlan-Abyss sandwich is….

Well–it’s a demizone of smoke, steam, dust and mud. An elemental transitional zone.

[SPOILER]And the individuals from all three planes start intermixing in volume II[/SPOILER]

There is no sentience in the 5 pure Elemental Planes–that we know of–although you gotta wonder about the plane of Spirit. Remember it’s the interaction of these planes that creates mana, animus etc. So a “pure” plane isn’t going to generate life or magic on its own.

The demi-elemental planes seem to be different. There are sentient beings that live there. I think they are ‘native’ but not really sure. But certainly since they are transition zones, they have elemental mixing which could create life and magic.