When the Elves discovered the small temple with the green door, my main concern was how they could open it and gain access.
Brute force doesn't work, and apparently, neither does magic. So, maybe a trick?
Until I looked at the image of the small temple at one point and noticed that at the top of the door was an iconic image of a face wearing a crown.
That was it!!! Only beings of royal descent could gain access to the temple. Or in this case, beings with an artifact of royal descent.
See? You don't always need an answer; sometimes the story writes itself.
