The astronomer/astrologer/seer of the lair, Celestis was one of the Aethers who took up the challenge to try to see the sky from closer up, and having returned, he wanted a place where he could continue analyzing the sky without expecting to alter his behavior to fit any particular norms beyond the practical. In the Haven, he has his own observatory tower at the top of the tallest magma spire, the position giving him excellent views so long as there aren't either storms from the north or plumes of smoke from the south... well, at least he can operate however he wants, so that makes it worth it.