Which descriptor fits a person who uses cunning tactics to achieve goals?

The descriptor that fits a person who uses cunning tactics to achieve goals is "devious." This term is often associated with someone who employs underhanded or deceitful methods to manipulate situations and people for their advantage. A devious person might be skilled in using tricks or dishonesty to reach their objectives, reflecting a strategic mindset that prioritizes outcomes over ethical considerations.

In contrast, the other descriptors paint different pictures. A diligent person is characterized by hard work and perseverance, focusing on consistent effort rather than manipulation. Capricious refers to someone who is unpredictable or changes their mind impulsively, lacking the calculated approach associated with cunning tactics. Benevolent describes someone who is kind and well-meaning, often focused on the welfare of others rather than using tricky methods for personal gain. Thus, "devious" stands out as the most fitting term for someone skilled in cunning tactics.