I watched Avengers : AoU and there was this scene where Scarlet Witch messes up Thor's mind. So after few scenes he finds Erik Selvig and they go inside a cave where they find a pool. Thor baths in this pool and starts sending out electric bolts and the images of bad dreams that Scarlet Witch gave, start appearing. What was this scene all about? What was this pool made of? How did Erik Selvig know about it.
I assume it was some anomaly that occurs where various realms meet as shown in Thor 2.