Treebeard is a very interesting addition to the game: he can be recruited in Fangorn by Gandalf, and he is then able to muster the Ents by himself, and raise them against the armies of the Shadow. He can also become involved in battles in the area around Fangorn and in Rohan.
The Treebeard promo figure can be used either together or separately from the Lords of Middle-earth expansion.