Arena mode is your chance to test your skills against 3 other human players in a 4 player tournament. However, unlike in PvP mode, you don't play against the other players at the same time.
When you take part in Arena mode, you play the mission and try to get the highest score possible. Once you've completed the mission, your score will be recorded on the scoreboard. Once 3 other players have completed the mission you will win rewards based on your ending position on the scoreboard, the higher you place the better the rewards you'll receive.
Some targets are worth more than others, for example: A fully armored soldier will give more points than a standard soldier, so pick your targets wisely as it could mean the difference between winning or losing.
If you're killed in Arena mode don't worry the mission won't end there you'll respawn again within 10 seconds, or quicker if you use Gold.
There are different types of missions that you can take part in, some use the Sniper Rifle while others may use the Pistol or Shotgun. The missions will have different objectives, some involve eliminating escaping, or attacking Elite Order soldiers, while other objectives include taking out enemy snipers or protecting civilians.
This mode can be accessed by tapping the “Arena” button on the left side of the main menu.