'Borderlands 3' DLC: Level Up Your Vault Cards and Get a Diamond Key as Reward—Guide The recent rollout of the "Borderlands 3" DLC comes with new additions to the game, such as the Fallen Heroes Vault Cards that grant experience points for players and Diamond Keys. Photo : Christian Petersen/Getty Images The recent rollout of the "Borderlands 3" DLC comes with new additions to the game, such as the Fallen Heroes Vault Cards that grant experience points for players and Diamond Keys--which rewards heroes with Legendary armor sets and more. Getting these rewards will put the player's skills to the test, as it requires them to grind the game like never before. In this article, we will tackle how to level up the Vault Cards that will lead players to the Diamond Keys in "Borderland 3" Director's Cut DLC.