Traditional sword and sorcery, with enough twists to keep me interested
I think it is fair to say the setting is inspired both by Tolkien and the Celtic (e.g. Mary Stewart) take on the King Arthur/Merlin myth.
There are some interesting plot twists that also serve as character development.
As someone who grew up around the time the book was written, I found the "New-agey" take on magic a bit jarring. Reincarnation plays a big role, as do things like "the astral plane" and "auras". It might be just me, but it feels like that terminology ties the book to the 1980s a bit.
Full credit to Kerr for giving her female protagonists agency and complexity in a way that works in a traditionally patriarchal setting.