|This is the multiverse. It's a straight line and the Prime Material is Now. Have fun!|
It's a nice little exploration into time, and it got me thinking.
In the traditional D&D cosmos, we have a Material Plane (both Prime and Alternate, of course), Elemental Planes, Astral Planes, etc. While reading the above linked post, the bit about the hell hole Earth used to be - asteroids, volcanoes, magma and such - got me thinking about the Elemental Plane of Fire. I guess really it sounds more like the Para-Elemental (or is it Quasi-Elemental? Dang you Gygax!) Plane of Magma. Either way, it made me think about a system whereby there are no alternate planes, just alternate times.
Plane shifting is actually time shifting, and everyone who is anyone throughout the history of the cosmos wants to get in on the here and now (i.e. the current campaign you're running) because it's super bitchin' and has stuff like assassins, manticores, coffee, magic swords and polymorph self.
So those fire (and magma, and lava and whatever) elementals do not come from the Plane of Fire, they come from many millions of years ago, representing the dominant life forms on Planet X (or whatever you choose to call the place where fighters slay dragons and thieves remove traps in your campaign) when it was just a ball of hot rock beset by asteroids and volcanoes. Water elementals and their ilk come from a more recent past, when the planet was covered by oceans and the only annoying material lifeforms they had to contend with were microbes (ah, the good old days). When a magic-user conjures them, he is plucking them from their own time and dropping them against their will into the here and now.
|Metron or Planetar?|
It could make for an interesting variation for your campaign. If you keep the secret of the universe from your players (and they don't read this post) it might be enjoyable for them to slowly piece it all together and, if they become high enough level, to try to bend the system to their advantage. It also gives entities from the recent future/past a reason to be messing with their recent past/future, as they seek to bend the system to their own advantage, with the hapless PC's caught in the middle.
Something to consider.