Núrzum is dead, but the enemy still roams free throughout much of Wildermore.
'Hail, ${PLAYER}! Your valour drove back Núrzum, but the forces of Isengard do not seem to care that their leader has fallen. They continue to swarm our lands in great numbers.
'The enemy is especially strong in the Writhendowns today. Go there, and show them that Wildermore will endure!'
The forces of Isengard can be found in the Writhendowns.
You should ride to the Writhendowns and defeat the enemies of Wildermore.