Niccolo Machiavelli was an Italian political philosopher. He is famous for writing The Prince (Il Principe), a book written to instruct a prince (his patron) on how to get ahead in the world.
He advised that the prince use any means available to take advantage of anything he that could... For example, encouraging warfare between other territories so that they would be too weak to attack him, and be easier to attack if the opportunity should arise.
Despite the fact that Machiavelli also wrote other, less controversial books, and the fact that some argue that The Prince was at least in part satire, Machiavelli's name has come to refer specifically to the tone of this book. Today, anyone who manipulates or takes advantage of another can be called Machiavellian.
If this isn't strong enough, you might want the word 'Svengalian'.