Currently I have a player who has made an assassin. As many assassins do, he loves to hide around in the shadows, and pop out on an unsuspecting enemy and do as much damage as possible before dissolving away again. His preferred method of doing this is to place down a stack of assassin's shrouds on an enemy. However, while looking through feats we noticed one called Hidden Insight which had the effect of creatures not noticing shrouds when the assassin is hidden from them. I didn't see any mention in the rules about what enemies know when they are shrouded.
So, what exactly happens when an assassin places a shroud on an enemy? Do they know they are shrouded and thus more susceptible to damage? Do they know that an assassin placed it? Do they know where the assassin was when he placed it?