I'd avoid single shot mill effects for the most part, especially small ones like Chill of Foreboding. They don't do any significant milling, and seeing cards go library to yard annoys some players. If you must run those, at least make sure they're big, efficient, or you can guarantee worthwhile stuff (which generally means self mill. Might not be in theme for you). Keep in mind options like Jace(s) are not terribly likely to live around the table, and it's a stretch to say that Glimpse the Unthinkable is worth 5 mana. I ran Dralnu as a mill deck for quite some time, so I do have some idea of what I'm talking about.