A "house rule" when you are playing Risk and run out of Infantry, (worth 1), but have calvary (worth 5) and artillery (worth 10). Therefore, you have to
manipulate "Manchange" with your adversary. When desperate not to "over bet" on a territory you may loose, you can
negotiate trades, even (1 for 1) or "
rough trade" (3 for 5) or (7 for 10).