As living story content, the dungeon will be available only for a set amount of time. Because of that, it can have pretty neat rewards -- "really cool ones" that "you'll want to come back for." There's no need to run the dungeon multiple times to get the whole story, but folks who do go in multiple times over the course of its presence in the world will find that it changes over time. There's variety in some of the things that happen and combinations of enemies in order to give players the feeling that they're not just ransacking the same facility over and over. To reinforce that, the entrances and exits to the dungeon will be moving throughout the cycle.