River Anduin
The Road Darkens#77 (x4)
Location
2 (5)
River.  
While River Anduin is in the staging area it gains: "Forced: At the end of the travel phase, each player at this stage raises his threat by 1. Then, River Anduin moves to the staging area to the left, if able."

"Anduin flows faster than I thought." -Aragorn, The Fellowship of the Ring