My very first book review, and it's for one of my favorite authors.
C.S. Friedman hasn't written a whole lot of books, but what she has done has just about all been top shelf science fiction.
A few notable favorites would be Madness Season, where an immortal creature that can assume the shape of any animal, but is allergic to sunlight and must survive on the nutrients in the blood of other creatures (a vampire basically) must learn how to survive in a universe where the human race has been enslaved by a reptillian hive-mind race. And the Coldfire Trilogy, which features a planet that was started as a human seed colony, except the colonists found upon landing that there were forces that would act on conscious and unconscious thoughts and effect the physical world. Thus if you had a doubt that something might not work, it would be amplified, and definitely not work. Hundreds of years later, it's become a fantasy world, where people use guns in favor of swords, since they are more reliable, and people are able to tap into the ambient energy in order to perform magic.
Feast of Souls is the first book of the Magister trilogy, and is a pure fantasy setting, which is a first for Friedman. In this world, there are people who can perform magic, but the cost is high, for every magical working, a bit of the casters life force is expended. Small things may only cost a few seconds, but larger workings could burn off hours of their life. These beings are called witches, and their eventual fate is to die young in old bodies.
Witches are not the only ones who are able to do magic, however, there is another group, called Magisters, who are somehow able to perform magic without having to expend their life force, and as such, they are effectively immortal. It comes to be known that in order to become a Magister, one takes a witch, and has them expend all of their life force, then once they are about to die, they will find another life force, and live and perform magic off of it, until it is gone. Magisters are exclusively male for whatever reason, (the hypothesis is that women are programmed by evolution to want to nurture life, and are therefore unable to bring themselves to live at another's expense) essentially a prerequisite for being a Magister then is that one needs to be selfish to the point of believing that one has the right to live no matter what.
The primary concern that Magisters face is boredom, no mortal concerns matter to them, since they can just outlive any enemies that they might have, and their are only so many places to go and things to do in the world. Onto the scene comes one very stubborn woman who is determined to have the power of the Magisters no matter what the cost. And an invading species of creature that devours life force in a manner that the Magisters find a little too close to their own methods of finding power.
It was a very fun read, with lots of political angling, and intrigue, as well as heroic prostitutes and knights in distress.
If you like fantasy that's a little bit dark, I'd recommend checking it out.