Proofing rules or instructions requires someone who is familiar with the topic/subject. Unfortunately, that very familiarity will also lead to overlooking minor issues because you know what is intended. Which is why you also need a relative novice who will say "Huh?" and get the experienced eyes to see the potential confusion.

Well, HeroClix is basically a game with very simple and clear rules. Then we have a whole bunch of stuff that are exceptions to the basic rules, i.e. they break the rules.