From Yen Press:
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.