This method is really just a flagrant abuse of the diplomacy system, but you need to be absolutely loaded for it to work. As such, it is only effective when your empire is in control of 30+ territories.
First, you need to recruit a diplomat and send him to the faction that you wish to contain. Then, bribe a small army and use it to declare war on faction X. You'll almost certainly lose this army, but that's extremely unimportant.
After you've successfully angered X, use your diplomat to force them into a protectorate. This is where the money comes in. The going rate for a faction's freedom on Hard seems to be one million mnai. Anything less always seems to get turned down. This may seem like an obscene expenditure of money, but the beauty of the protectorate system is that you'll immediately recoup just about all of it as tribute. As a result, X will be flat broke, as all the money that it would have received via scripting would instead go straight to your coffers. X will be unable to train troops and will stagnate and eventually decline. Once equilibrium is reestablished, you can just diplomatically end the protectorate.
Any thoughts?
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