In the level, Hidden Path in the White Mountains with Gandalf, walk around the level killing things. When you reach the uppermost path where your pointer points straight right, go left, break open the barrels, and walk around the ledge. Then backtrack back to near where you started the level. On the path going across above where you started above a waterfall there will now be a cave. Go in and you will be in a secret spot with a Ranger Hollow and a troll, along with drummers, crebain, and barrels.