Mount Keru.
The party follows where the luminous beings beckon- as they get closer, they can confirm, these are definitely humanoid, glowing with pulsing color.
Even closer and.. pointed ears???
The glowing beings are fuzzy and indistinct, but there is enough detail to observe, at close range, an Elven build. And when you can see ears clearly, the iconic Elven points!
The building they are summoning you is definitely unlike the rest. All of Mountain Elf architecture is designed to be graceful and airy, and admit as much light as possible into the interior. This one is different. While it is still clearly a Mountain Elf structure, and shares most of the common design elements, it is almost entirely opaque, and has only a few windows.
There are colorful decorations on the slender pilasters surrounding the front door, which is open. Cornucopias. Here, as in the lands of other cultures, it is the common symbol for agriculture, and by extension the goddess of agriculture. But this is no temple.
Inside, it is dimly lit- the dawn's light is still weak, and not yet enough to spread much light through the doorway and narrow windows.
In the darkness inside, the beings are more clearly seen, and they certainly do seem like Elves. They are made of light, glowing and transparent. There is nothing solid to them.
Shape without substance, they could be the opposite of shadows.
It is only there that you hear them speak, in Elven. Their voices are strange. A being- it has the shape of an adult male Elf makes a graceful twirl, like a dance move unaccompanied by music, and the voice seems to come from the air in front of it, a projected sound.
But only a quiet whisper.
"Have you come for us? Are there more of you?" it asks.
Another, behind, "speaks" in the same way, invoking sound from the air with arcane gesture and movement.
"It has been long, and we grow weaker. Please say you bring good news."