Because I am ramping up my unnamed GAC/Pulp campaign, I have been re-watching a lot of serials and re-reading a lot of pulps. In "Pulp Hero" 5Ed, Steve proposes the obvious solution to the Shadow's ability to ability to vanish by 'clouding men's minds' -- invisibility. Various versions are presented, but there is a suggestion that the GM optionally allow a +1 PER to detect the character for every 5 points of Mental Defense that the person has. That's totally in keeping with the power, those with strong minds can see through the Shadow's 'invisibility'.
That mechanic (while elegant) doesn't work for me. It doesn't take in to consideration merely those with high EGO and, from my perspective, it doesn't really fit the way we do things as a general rule (maybe I'm over analyzing). So, how would you write up Invisibility that can be perceived by those "with enough will"?