The Battle Pack is a feature that allows you to get diamonds, coins, power-ups and unlimited fuel! You are going to fill it with the rank points you get in the battles you play and once it’s filled, you can open it with diamonds - which you get back by opening it!
Furthermore, the more Battle Packs you open, the better they get, since you level them up!
Don’t forget that once they’re filled, you have up to 48 hours to open them, or they will reset. If you’re in a rush and you don’t want to wait until it’s completely full, no problem! You can open it once it reaches 50%, but be careful: you’re going to get fewer diamonds when doing this.
The items you earn in the Battle Pack are placed inside your inventory.

