[MnM] How many Incorpreal/Invisible/ etc. characters do you have in your games?

[Petrosian]

and if two people are doing that, who's to say they might not be on the same "frequency"?

I tend to define that interaction by the fx of the two powers. A scientist's densitometer ray would not enable him to interact with a mystic's astral projection because their FX are so dramatically different.