So far we know very little about Mithyn, other than she appears to be some kind of divine being or goddess. During the interlude between chapters 2 and 3, she discusses Zelica's captivity with Mystery Divine Being as well as a mysterious tower that seems to be what broke King Alonon's spirit when he looked inside.

Given Vera's impression that the Goddess of Magic has wings, Mithyn is a candidate for the role. Another possibility is that she might be the "Mother of the Succubi" of elven mythology, assuming that each goddess created her race in her own image.

Mithyn full

Full view with more of her wings. (Click for larger.)