The Arena is the place for the players on the server to prove themselves against each other and reach the highest rank.
You unlock the option to fight with other players at Lv 24.
You get 15 tries daily to challenge players 10 ranks above you.
After each fight there is a 5 minute cooldown (you can't attack anyone during this time), which can be removed by using gold or coupons.
You get different rewards depending on your position. The higher rank you are the better the rewards, which include prestige, silver and material chests.
Arena reward can be claimed at 19.30 GMT-6 (Chicago) or 01.30 GMT.
Also, the players you defeat can be found in the Defeated List in your Master and Slave option, you can battle with them to attempt to capture them.