What is Player vs Player?
Player vs Player (or PvP) is a combat feature where players compete against each other instead of against creatures. Similar to dueling, Player vs Player dueling is a much more in depth method of matching your skills against other players.

Each period of competitive PvP gameplay with ranks is called an 'Age'. These ages are sometimes relatively short, and sometimes they will last even for years. Once an Age ends and a new one is begun (announced by the developers), your Rank will be reset with the new Age.

   The Player vs Player Arena is located in Unicorn way, inside the current dueling arena.

Just look for Diego, he's standing next to the entrance. Inside you will find two pedestals with Scrolls on top.

  
The Scroll on the right is for Practice Dueling and all players can participate in this.

  The Scroll on the left is for Ranked Dueling. These are duels that can earn you Arena Tickets and are only available to Members or with Crowns on a Pay-as-You-Go plan.