Is there a script that prevents a specific hero from acquiring a particular skill? I have the following situation: there is an artifact hidden on the map that needs to be found, but it is hidden in such a way that a hero with the "Silent Stalker" skill will discover it too quickly, which I would not like. Moving the artifact to another location is not possible, as this would require rearranging many regions.

Added after 19 hours and 57 minutes
Or, please tell me how to prevent the fog of war from disappearing in a specific area of the map, as in the last mission about Argil? I read about this, but unfortunately, I didn't really understand it...