Aggression in MOBA games is a well-known problem that is still relevant. How to deal with it? Opinions differ. Some consider it an inevitable feature of the games of that genre, while others attribute it to the players themselves. In this book, you will get acquainted with a unique view on the causes of aggression in online games and MOBA games in particular. Based on the psychological theories of aggression, the peculiarity of Internet communication, and players' immersion, the author deduces a list of factors of aggressive behavior. Those factors are used to estimate MOBA games' current problems and help to reduce aggression in released or developed games. In the second half of the book, the Dota 2 game features are analyzed in detail. The research highlights many areas where changes can help reduce in-game aggression, ranging from the time for resurrection to the rules formed among the players. There were as well identified five types of players according to their in-game motivation. Based on analyzed data, recommendations for Dota 2 are given, which can be valuable for all MOBA games inter alia.