Zor'be the Bloodletter at the Argent Tournament Grounds wants you to kill 15 Icecrown Scourge. You may kill Scourge in any part of Icecrown except the Bombardment.
15x Icecrown Scourge slain
While we all play at mock combat, it will do us good to remember that the real enemy surrounds us. The Argent Crusade wants to use competition to find the best fighters, but we can tell that by who returns from battle. Let's show the paladins that we are willing to take battle to the Scourge, even while making preparations for the tournament.
Go forth into Icecrown and slay any of the Scourge you encounter. Stay clear of the Bombardment. It is already under attack from the air.