Veet,
thank you for your feed-back. I'm glad to see that some of my hopes and some of my doubts were confirmed by your playtesting. The double Dark Young movement should stop as soon as I apply Avi's suggestion to avoid enhancing cultists. I know in a Shub game, 7-toughness Dark Young (when in aerial locations) are a little too heavy, in case they appear too often. About restricting some areas for them to move in, I was thinking about the chance to restrict Asylum and Hospital too. I should update the Herald probably tomorrow (this week was pretty terrible), with some modifications about Dark Youngs.
Again, thanks a lot!