Does anyone remember what the levels of reality were, that was referred back to in Door To The Unknown where the Mercurials came from? From what I remember the standard reality was the 3rd level of reality, and 'hyper-reality' was the 4th.
I think one of the Ravenloft products actually defined them with the 2nd level of reality being the dreamscape...
Anyways I'm thinking of making the 4th level of reality to be the 'spirit realm' of the MotP/OA, and the 2nd level of reality to be the Dream Planes from both MotP & the Dragon article (which I sort of came up with a way of reconciling all the different versions).
Part of my idea actually came from the old WOD cosmology of the different Umbras and such...
Level 1 reality is common dreams or brief visions out of the corner of your eye. Everything is fleeting and insubstantial. Dream-selves can be injured or killed without hurting the dreamer.
Level 2 reality is dreamscapes. Things that happen in dreamscapes affect the dreamer as well - if you die in a dreamscape, you die in reality. Dreamscapes can sometimes escape the Plane of Dreams and slide into the Ethereal, becoming permanent.
Level 3 is the waking world.
Level 4 is hyper-reality, as in the realm the mercurials come from in "Doors to the Unknown." Everything is brighter, sharper, and realer. All damage, spell durations, range, areas of effect, and so on are doubled.
Level 5 is beyond the reach of mortals. It's where gods go when they've evolved beyond greater power status, ascending beyond the multiverse we know. Perhaps it's what the Athar call the Great Unknown.