Brain Ball mode in PvZ is a new game mode while is released just recently. Before this, it was actively developed and tested by the community in testing environment which can be reached at https://apps.facebook.com/PvZatestclient/. The game in this testing environment is just temporary and the account will be reset so testers are advised not to overly indulge in it. This mode shall be a new highly competitive game mode which will attract more players to compete among their neighbors.
Plants vs Zombies Adventures Brain Ball mode - Mechanics
The new mode has the idea of standing by Zombies’ side rather than the usual Plants’ side. Instead of growing Plants, you now train Zombies with Coach Zombies to invade Neighbor’s Town and grab their Brains. There are many Zombie Types you can train and just like growing Plants, various Zombies have various complete times and you can bypass this process using gems. Remember that you are not just the offender but you must defend your Brains too from being grabbed by your Neighbors. You are given Brains and you can choose which Building you want to hide them. You are allowed to put multiple or even all of the Brains in one Building or House but putting all eggs in one basket is risky since all of them may be grabbed in one-go unless you have extremely tough defense on the particular Lot.
There is a time limit for each round. There is also a Leaderboard to show the ranking of the Players who have participated in Plants vs Zombies Adventures Brain Ball mode contest and the higher the rank you are in, the more gems you will get when the time counts down to zero. In order to win the game, you need to get the most Brains from your Neighbors and avoid your Brains from being grabbed.
While attacking Neighbors, you have a total of three waves which means if you fail on one wave, you can pick other Zombies and start another wave. You will gain advantage on each subsequent wave since a new Grave starting point will show up on the farthest point the Zombies reached during last wave. This mode is similar to Send Zombies but take note that you are not putting Zombies right away but you need to prepare and train them before hand.
For a complete guide on PvZ Adventures Beta, go here.