@GangorraAidetica I understand your idea, I explain to you, the price change of the mysterious box as I remember in a published post created a thread for each player, basically it works, but it is not the right thing, since the server will create a thread for each player and here is the point, each player will establish the price of the mystery box, instead the correct way would be to create a level thread and only with a single thread would the price of the box be established for all players and thus be avoided create a thread for each player and redo with threads that do the same and also avoid saturating the server with unnecessary threads. I hope you have explained me.
Instead, in your case, what you need is to manage the values of kills and deaths of each of the players, for that reason a player thread is necessary. Since the kills and deaths are unique for each player that connects to the server. Unlike the price of the box, a level thread is needed because the box is the same item that will have the same properties for all players.