It's a stupid thing really, but I can't seem to wrap my head around this one. Please don't tell the people who hire me to edit their texts!
So in my Euro-game, one of the actions is contributing to a building (think Caylus or Egizia). There are four buildings (temple, castle, university, and fortress), and each of them is shaped like a 4 floor pyramid: first floor has room for 4 contributions, second for 3, third for 2, and fourth for 1. The cost to contribute is (a) as many resources of the buildings color (temple is white, castle grey, university blue, and fortress red, and those are the colors of the four resources in the game) as the floor on which you're building (first floor is 1, second is 2, etc..), and (b) two other resources, which are different from one another, and different from the building's color.
So far the best I've come up with is "For each contribution, you must pay as many goods of the building's color as the floor on which you're building, and two other resources. You must use a total of three different resource types." However, I also have a fifth resource (money) which is wild, and it does make this rule untrue.
Anyone can do a better job than me?