In my campaign, there were once three elven queens, mighty in lore and sorcery.
Each of them went supercritical and blew a piece of the campaign world off the map. We’ll get back to this.
There’s this thing in D&D where the planes are exceedingly clinical. It cuts off adventure: these are the demons, and they call themselves the Tanar’ri (which means I need to call my elves the Erdoëri, doesn’t it?) and the 1st layer of the Abyss-their-home is suchlike, and the 66th is suchlike…
And that’s the Abyss! the infinite, the unmappable! Every single other plane is even more clinical, because the entire plane is described in a few words. It’s the fantasy problem of the Nounworld writ large; to make the land have a specific character, we need to describe it, and so we describe it, and so we have summarized entire worlds in the space of a paragraph.
I don’t want that for my campaign. It’s a little hard to avoid (after all, everything has to have some sort of summary, right?), but I don’t think it’s inevitable. So I took steps: the world where your character was born is, as is traditional, the Prime Material Plane (the Prime for short). No more need be said about it.
Then, there is the Nether, the ocean which touches all shores. This is the plane of mists and shadows; the echo of what’s real. It combines the properties of the D&D-classic Ethereal and Shadow planes; a sort of funhouse mirror of the real world haunted by spirits. It’s a very “physical” other world, if that makes sense: it’s a place you can go, and while the rules are different (most real-world objects are like mist in the Nether, so you can sort of swim through them), your body works the way you expect and physics are still physics. An observer in the Nether perceives objects in the Prime mistily, and can will themselves into the Deep Nether to step around such objects. The more “worked” by human hands an object is, the deeper into the Nether one will have to pass to circumvent it; a living being may be bypassed with little effort, but the written word cannot be bypassed without risking being lost in the Deep Nether. There are currents and undertows.
The prime also has a “Twin”. There’s a somewhat-primelike world which shares our region of Shallow Nether called Gehenna. It’s a twisted hellscape, of course; it’s also known as the Dungeon Dimension, the Wormworld, and Hell; it’s a prison and a torture chamber. More on Gehenna later, but note: it’s the ultimate funhouse dungeon, a twisted and ancient ruin filled with magic, danger and treasure.
Of course, I have the worlds of angels and devils, ifrit and djinn. I mean, that goes without saying, surely. But let’s get back to the topic of elves. Three elven sister-queens, Fymory, Illyria and Yaralay. Each as an avatar of destruction. Each as the mother of a world. I’m sure there was a reason for that digression into the Nether and Gehenna, and the nature of the planes.
Fymory is the largest coherent realm, a single magical kingdom two hundred miles on a side with a shared culture and language. Of course, it’s ruled by the mortal-hating Fomor and haunted by the goblins and other creatures who serve them. It was taken entire into twilight, with every living creature, several hundred years ago. Its edges are high and misty mountains, and it has no sun, but its high moon rotates through a period of gloaming each “day”.
The courtiers of Fymory are “unseelie” elves. They’re kidnappers of children, they’re enchanters of sailors, they’re tempters of the faithful. They also have with them all the fruits of the old Elven empire: so long as they’re exposed to the Fomor Moon each night, their goods remain magically potent. Their shoes are invariably boots of elvenkind, their cloaks of elvenkind, their armor mithril, their weapons the same. If they’re removed from that place, they fade: often still retaining some magic, but occasionally turning to ditchwater and leaves.
Lycanthropy originated in Fymory as a weapon against man. Humans taken into Fymory are often transformed into beasts, so you encounter a lot of bestial hobgoblins and bugbears in that place (since they’re beastie people, or at least close enough for me).
Illyria is the next eldest, slightly larger than Fymory, and extremely disjoint. When Illyria went critical, her bloodline was caught up in the swell of wild magic. Whole islands of the Pessuary island chain disappeared; deep forest glens and hidden vales; mountain peaks and dark grottoes. The denizens of Illyria are place-spirits, and the boundary between one of their realms and the Prime is often a loose one. Each of the Illyrians can navigate their genealogical tree somewhat, visiting with their kin or sending travelers to visit with others within their myth.
Each of the realms of Illyria is different, and feels like (wait for it) a fairy tale. The logic is warped by the Illyrian inside: they’re a sort of petty god within their domain, but generally a very limited one. The Event that gave them their power also limited their conscious control of it, so visitors have to navigate the rules it defined.
The actual island of Illyria herself can be reached from certain sailing patterns in the Pessuaries, under the correct stars. She is a retreating hostess, and those who have returned from her realm report a land of timeless ease and vegetal wealth.
Yaralay is the truly eldest realm of fairy. Physically, it was once at the northern pole; its destruction marked the creation of those now termed the Sea Elves. It is rumored to be an aquatic realm, dark and strange. Rumored: because all gates which reach it from the north lie within what is now Iutenland, and the giants have no love for the elves.
The important piece of tech here is that these are sort-of-kind-of countries. While they have laws-of-physics style overarching rules, that’s not the point. The point is that Yaralay is an elf-land, but a specific elf-land: a cold and blasted aquatic realm, unknown save for its shores. Fymory is well known, and we’re at war with them. Illyrian realms are places of natural beauty or fairytale logic, and their inhabitants are a little tragic (because they were plucked from their lives in a breath, due to the influence of their queen-and-mother).
So: no map. A classification maybe, but each species can buck the genus.