The elves of Tellest are the people who have lived among the surface longest. Because of a fear of their neighbors, they enacted a ritual that drained Tellest of magic for millenia. Their curse, now, is that the magical gifts they once had are shared, diminished in their use among the various tribes. Elves that could summon ethereal wings and fly into the sky are now limited by how long their wings can remain with them. A tribe that could teleport like wind on the leaves to anywhere on the planet they visited at will are now restricted to doing so twice per day. Consider your own tribe of elves that may have been hidden from the other people of Tellest, and write about their shared power.
Ideas and questions:
Some other examples of Tellest elves that you can use to piggy-back off of: a tribe of elves that can breathe underwater for a certain amount of time; a tribe of elves that begin to look like trees after they hold still long enough; a tribe of elves that can create scrying circles that last for several minutes, allowing them to talk to people across the realm.
You do not have to talk about the elves of Tellest as they are, with their powers diminished. You could talk about the events before The Fall, when all the elves had immense abilities, regardless of how many were in their tribe.
Perhaps you are looking at an elven tribe that think it too dangerous to use their powers at all, lest they cause some other sort of catastrophe. Or you might be looking at a group of elves who is trying to find a way to restore their gift, even if it is just to one elf among them at a time.
Is your story going to look into the bleakness of having a power that is diminished? Or will it instead look at how these powers can almost be harmonious, and that there is a certain amount of community in working together with what remains of these abilities?
Are you going to look at a day in the life of one of these elves or their tribe, or are you going to take a deeper dive, and go on a full-fledged adventure with the tribe, and see how they use their powers effectively?
Because the elves of Tellest have no natural life expectancy, their stories can span ages. Write a story that focuses on a very old elf who is telling members of their tribe what it was like when their powers were not diminished.