Often, multiple players will be able to turn in their risk cards in a row. These players will recieve an extra injection of armies and can really accomplish things on this turn that they otherwise wouldn't be able to do. Don't inspire them to accomplish these things against you; be quiet and build up your armies if a bunch of your opponents are about to turn in Risk cards. If they're not inspired to attack you, maybe they'll attack each other, and then you can attack them at a later time when they have less of a windfall of new armies with which to counterattack.