The Way Of Shadows: Book 1 of the Night Angel Weeks Brent (2023)

Azoth has grown up in the slums, where survival depends on judging people quickly and taking dangerous risks. One of those risks is apprenticing himself to Durzo Blint, the citys most accomplished assassin, for whom killing is an art. To be accepted, Azoth must abandon his old life and assume a new identity as Kylar Stern. He must then learn to navigate the assassins world of dangerous politics and strange magic while developing the skills needed to survive.