Jack is a techno-mage, meaning that he has the ability to control and manipulate stuff like metals, machines, and electronics, and can also hack any locks that he can get his hands on. He is also a mercenary for hire, working for anyone for the right price. For his voice, he would have a deep to medium voice with strong Australian accent and a touch of cockiness. Here's his theme to give you better idea of his story and personality: https://youtu.be/KFD3Rfo728U