I saw Lady-Protector by L.E. Modesitt, Jr. at the library and had to check it out. It is the latest book in the Corean Chronicles. There were seven others before this.
The world of Corus has a funny sort of magic that was used by the Ancient peoples that are native to it. It can only be used by certain talented humans and what is left of the Ancients.
Corus was invaded by a group of selfish and extremely arrogant aliens who travel between worlds. They use a worlds life force for making and building things. When it is all used up and everything is dead…they move on to another world.
The Ancients and some talented humans have kicked them off the world in the past. They are trying to come back. One human – the current Lady Protector is trying to stop them. She is also having to deal with an invasion by another country and traitors in her own country. This is part of her story.
This is a really good book. All the books in this series have been good. I also like many of Modesitts other books. Particularly the Recluce books and the Imager series.