[quote=@Fabulous Knight]
[@Hael]It's worth noting that to use detect them using occultism, you'd have to set up a ritual. You couldn't passively see them, as it were -- and you'd have to know where you'd be looking.
[/quote]

That does make it unbelievably difficult to detect them. By the time the ritual's almost done, the dudes would know it's being prepared and would likely flee to another place.