Vault Cards give some of the best rewards in Borderlands 4. They unlock gear, cosmetics, and strong boons that matter a lot in the late game. Leveling Vault Cards can feel slow if you only run random fights. To speed things up, you should chase the highest XP-per-minute content and repeat the fastest loops Borderlands 4 Cash. How Vault Card XP worksVault Cards level with your Guardian Rank, so...