It is my belief that she is Cyndane(appearing in PoD). First off, if she AND Moiraine fell into that doorway, then wouldn't Lanfear find an opportunity to kill Moiraine? Surely she would. It's already been established that Thom will rescue her, so she can't be dead. That would only mean that Lanfear died, and was reborn. A lot of people think that Asmodean is in the second mind trap. Why??? What use could it serve? Lanfear in the mind trap, on the other hand, would serve quite a bit. Remember, Graendal was surprised by Cyndane's strength, and Lanfear was the most powerful female Forsaken.