A Superhero's Legacy by Lucas Flint

On his sixteenth birthday, Jack McDonald receives a mysterious watch from his long-lost grandfather. He discovers that his watch can turn him into the superhero
Trickshot, whose powers he uses to save his classmates from a gang of drug dealers.

It turns out that Jack's grandfather sent him the Watch so Jack could become the superhero Trickshot and defend the city from a dangerous threat. But Jack has other purposes for the Watch in mind, such as avenging the death of his older brother at the hands of the evil Injector drug cartel.

Now Jack must learn how to use the powers the Watch gives him in order to defeat the Injectors and avenge his brother.