The #'s on the map(s) show the areas where the first few steps in each task takes place (Same #'s take place in the same area, if no # is present it is an instance, takes place outside of the zone, or can be done throughout the entire zone)

Tasks go in - order, if an | exists it means you can do those in any order, but have to all be done to continue on to the end. If tasks aren't listed in a chain, they can be done at any time.

Quest Chain: This Is Argath - Shoring up Defenses - Protect the Arms - The Riddle of Steel - Breaking Ballistae - Critical Mass - Reclaiming Argath - Illdaera's Vengeance