Reference article
Arena (Duck Life: Battle)
The City Arena is designed for battles against other players’ stored duck profiles.
How it is designed
The source uploads duck profiles, retrieves opponents and records results through an online service. Opponent profiles become opponents in the local 
Battles system. The interface includes daily, weekly and monthly leaderboards.
Availability
No live Arena request or current released-build gameplay check was performed for this reference. Service availability remains to confirm; the source alone does not establish that the Arena currently works on every platform.