Brawl Stars is a game that lets you and your friends battle it out in a number of different arenas. The gameplay is based on the concept of fighting, in which you and your opponent use physical strength and skill to fight each other. It is a game that is easy to play, but with a number of different options and gameplay modes, it has a lot of depth.

How many boxes do you need to open to get a new brawler?

The game doesn't let you know when you will get a new brawler. It is only given to you in the form of a number, which is the probability of getting the brawler.