Arena

The Arena, surprisingly, is what you select when you want to enter the Arena game mode. Arena uses the same hero combat system as Conquest mode (found in the Conqueror’s Camp building) but replaces AI opponents with teams built by other players. Each day you receive a limited number of Arena challenges.
Every challenge attempt provides rewards regardless of whether you win or lose, while victories grant Arena Points that improve your ranking and increase your daily and weekly rewards. You do not lose Arena points when you lose an attack, only when another player defeats your Arena defense formation, so be sure to keep it updated with your best heroes (see our hero tier list for suggestions)! Rankings reset each week, allowing everyone to compete again on relatively even footing.
Especially during your early progression, it's always worth using all of your daily Arena attempts since there is little downside to participating, and you are giving up free resources if you do not use them. Please note that Arena mode uses different stats and hero abilities than Expedition mode (simulated combat on the world map).
This building has no upgrade levels.