Bitter Night by Diana Pharaoh Francis

In Bitter Night, Diana Pharaoh Francis takes the reader into a fantasy world.  But this is not a pleasant fantasy.  This world is brutal and violent, where loyalty is given by compulsion spells that cannot be broken and everyone is out to best those around them. 

This world is controlled by witches.  Each witch has their own coven, and within their coven, they have soldiers who protect them with their lives, if need be.  The soldiers are of two types.  Shadowblades work at night, and can not withstand the light, while Sunspears work during the day, with darkness deadly to them. 

Max is the leader of the witch Giselle's coven; the Prime Shadowblade.  Giselle tricked her thirty years ago into giving up her human qualities to become an immortal being.  The problem is that she didn't tell Max that she would be giving up her life, her family, everything she loved.  Max hates Giselle, but cannot leave or disobey her orders. 

Now, in addition to the battles between witches, an even greater danger looms.  The Guardians, lords of all, have decided to bring down ultimate war and cleanse the earth of all humans.  To do so without destroying the earth, they need the obedience of the witches.  Both Giselle and her arch-rival Solange resist the Guardians, and their angels of destruction. 

Can Max and her crew manage to survive this new threat?  What kind of relationship will emerge between Max and Solange's Prime whom she defeated in battle and then recruited to her side?  Will the Guardians be successful or will the witches emerge as the new ultimate authority?

This book is the first in the Horngate Witches series.  It is recommended for sci-fi and fantasy fans who don't mind extreme violence.