Perkembangan teknologi permainan dari analog ke digital memunculkan bentuk interaksi baru melalui Computer-Mediated Communication (CMC). Dalam konteks ini, pemain dapat berinteraksi secara anonim, sehingga lebih bebas mengekspresikan emosi, termasuk kemarahan dan perilaku negatif. Hal ini semakin nyata dalam game bergenre MOBA yang bersifat kompetitif, di mana kekalahan sering memicu frustrasi. Ujaran kasar dan perilaku destruktif yang muncul berdampak pada psikologis pemain serta kualitas kerja sama tim. Penelitian ini bertujuan memahami proses terbentuknya perilaku toxic dalam game Mobile Legends melalui perspektif CMC dan teori deindividuasi. Penelitian dilakukan dengan pendekatan kualitatif dan menggunakan metode fenomenologi. Penelitian ini menggunakan teori deindividuasi untuk menjelaskan fenomena perilaku toxic dalam permainan Mobile Legends: Bang- Bang. Penelitian ini menggunakan wawancara mendalam terhadap tiga informan aktif dan juga observasi langsung. Berdasarkan hasil penelitian, permainan Mobile Legends: Bang-Bang yang dimediasi oleh komputer sering memunculkan perilaku toxic yang mengganggu kenyamanan pemain lain. Anonimitas dalam CMC membuat pemain merasa tidak diawasi, sehingga mereka lebih berani melontarkan kata-kata kasar atau perilaku toxic tanpa takut dikenali.Oleh karena itu, penelitian ini menyarankan pengembang, seperti Moonton, menerapkan sistem jeda bagi pemain yang sudah menerima kekalahan beberapa kali. / The development of gaming technology from analog to digital has given rise to new forms of interaction through Computer-Mediated Communication (CMC). In this context, players can interact anonymously, which allows them to express emotions more freely, including anger and negative behavior. This phenomenon is particularly evident in competitive games like the MOBA genre, where losses often trigger frustration. Harsh language and destructive behavior that emerge in these settings affect both players’ psychological well-being and the quality of team cooperation. This study aims to understand the formation process of toxic behavior in the game Mobile Legends: Bang-Bang through the lens of CMC and the theory of deindividuation. The research was conducted using a qualitative approach with a phenomenological method. It employs deindividuation theory to explain the phenomenon of toxic behavior in Mobile Legends: Bang-Bang, using in-depth interviews with three active informants and direct observation. Based on the findings, the computer-mediated nature of Mobile Legends: Bang-Bang frequently fosters toxic behavior that disrupts other players’ comfort. Anonymity in CMC makes players feel unmonitored, thus emboldening them to engage in toxic speech or actions without fear of being identified. Therefore, this study recommends that developers, such as Moonton, implement a cooldown system for players who have experienced repeated losses.