So Ares and Giant Man have special powers that say they can "use perplex" and "can modify a combat value only by two with each use". The wording confuses me a bit. Does this mean that when they use perplex they add +2 do a value and the value can't be raised by another perplexer, or does it mean they add +1 bnut the rule of 3 becomes a rule of 2. Thanks in advance for the help.

I believe that they can modify any combat value by +2. It does not stop another perplexer from perplexing that value up, but I think it would stop them from using ICWO on that combat value that they increased by +2

double posted. please delete.

It means their only option is to increase a stat by 2. They can't increase it by one, decrease it by one, or decrease it by 2. Other than that, all standard rules (including the rule of 3) applies as normal.