"Cult of the Vault" is a challenge from Tiny Tina's Assault on Dragon Keep DLC
The First symbol is found in in the Eastern portion of the Fields of the Fallen. Look for the Tower in that area and approach the Western face of it. You will see the Symbol right in front of you, above the chests.
The Second Symbol is arguably the hardest one to find. Head North into the Sacred Ruins. Get into the Northern ruins and then hop onto its Southern ruined wall. Head along it to the East the start jumping your way to the South. When you get to the big gap, move forward and drop onto the lower portion then move back agianst the wall. From there do a very quick running jump. That will get you across. Jump up onto the next part of the building carefully. Head over to the Right and to the far wall. Go to the outer portion of it and look on the Wall to find the Second Symbol.
The Third Symbol is in the Northeastern corner of the Cemetery in the Sacred Ruins Head to the Northeastern corner and look above the chests. There is a slope that you can use to reach it.
Ranks and Rewards
Badass Ranks: 5