After reading a lot about the "Big Unnoticed Thing" on dragonmount, I think we'll see the end of Slayer and learn a lot about him in the ToM. There is a big thing about the eyes of TaR, and Luc was noted by Perrin as smelling cold and almost not human, believed to be from entering TaR in the flesh.
I havent read the actual thread about the Eyes of TaR, just the Unnoticed things theory, so this may have already been discussed there. ( I like to read some of their ideas, then think of my own and see how they rate up later
) But Slayer jumps into the Tower of Ghenji in whatever book and Birgitte tells Perrin its evil (some theories have said the "eyes" are where Mordeth got his powers and hence Fain), so I think its very likely that the finns are the eyes and matt/thom/noal will run into slayer when they go to the Tower. Just my spin on things while trying to pretend I pay as close attention as the dragonmount people.