It’s been a long time since I opened it,so I do not remember it myself.
But from what I gathered in the Wiki, you will need to follow a Seelie to its home near the palace. Seelie will take you to all the torches, because Seelie are nice like that, and you’ll need to light them. After that, you’ll need to activate a Geo elemental monument.
Did you know that if you look at a Seelie’s home with Elemental sight, you will see the direction to the Seelie?
I say “torches”, but they are those special “ruin torches” that glow with weird fire when lit: