I was rather surprised by this turn of events. At first glance, Dreaming does not seem like such a powerful skill to use. However, I wonder if it can be used for spying: Egwene’s visit to the Stone of Tear certainly seems real enough. This would make it invaluable as a way to gather information. I can also imagine that it is helpful in maintaining contact between individuals over large distances: I wonder if that is how the Darkfriends could all meet together in the Prologue to The Great Hunt. I have to assume that Liandrin is not the head of the Black Ajah, so she would need to report to her superiors in some way, and this could be a simple solution to that problem.