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