As you explore the world of LBKR you will regularly bump into areas that trigger an Arena event, this can be thought of as puzzles or mini-challenges that require certain actions to be performed in order to be completed.
The arenas that are deployed on a map are randomized so revisiting previous locations is never a bad idea, as some of the more difficult arenas come with a chance to provide you with great and unique loot.
When you overcome the challenge of an arena you are usually rewarded in a number of ways. First and foremost the Bounty Keeper at Secure Command appreciates your efforts and you gain Bounty Reputation, by maintaining a good standing with the Bounty Keeper he will offer you better gear in his shop.
Furthermore you are most often given access to a rare chest or faced by a unique monster or boss that drops rare and/or exquisite items.
Some arenas might instead reveal secret areas or maps, and even wandering merchants who offer you their unique services and Items.