The Last Line Of Defense

This quest starts (and ends) a phase of The Argent Vanguard and the Valley of Echoes, where the scourge attack, with Nerubians, scourge of various sorts, and Frostbrood Destroyers.

Objectives
Use an Argent Cannon to destroy 100 Scourge Attackers. You must also kill 3 Frostbrood Destroyers.

Return to Siegemaster Fezzik should you succeed.
 * Scourge Attackers slain (100)
 * slain (3)

Description
I've triggered the base's defenses, ! Atop each of the Vanguard's four towers is a retractable Argent Crusade cannon, blessed by Father Gustav himself. You'll need to fly up to one of those towers and man a cannon. Use it to destroy the Scourge onslaught that the Lich King has deployed.

Just one warning, the Scourge will undoubtedly send their frost wyrms to lay siege the towers. Shoot them out of the sky! If they destroy the walls and towers of this base, we're done for!

Progress
The screams of the dying will haunt me forever! Help them!

Completion
You have handled the cannon like a goblin gunner, friend. You've saved the Vanguard and the Argent Crusade - all the while backing the Highlord himself up on the field of battle! Amazing!