This will come over time by progressing through the game's story and exploring the world. "Completing" a vault does not simply mean make it to the end and nab Zeus' lighting bolt. You must also obtain all optional chests that may be scattered within, and quest related items (there a couple here and there). Use the far sight mechanic (R3, or push and hold in right stick) to scout within a vault of Tartarus. Look for any beacons and mark the loot as you normally would in the overworld. You can check your progress under the achievements tracker.