The Night Angel Trilogy: Book 1: The Way of Shadows

For Durzo Blint, assassination is an art - and he is the city's most accomplished artist.
For Azoth, survival is precarious. Something you never take for granted. As a guild rat, he's grown up in the slums, and learned to judge people quickly - and to take risks. Risks like apprenticing himself to Durzo Blint.
But to be accepted, Azoth must turn his back on his old life and embrace a new identity and name. As Kylar Stern, he must learn to navigate the assassins' world of dangerous politics and strange magics - and cultivate a flair for death.