Multiplayer Online Battle Arena (MOBA) is an online game composed of two teams to fight each other's base to achieve the goal of the game. Each player must destroy enemy’s buildings and minions using their avatars, thus earning gold and experience. Responding to the sensation-seeking brought by the game, male adolescents are more compelled to play the game and exhibit aggressive behaviors. The study aims to identify the relationship between the level of aggression and the motivational systems, namely Behavioral Inhibition Systems and Behavioral Activation Systems. A total of 130 Filipino male adolescents aged 13 to 17 years old who play League of Legends (LoL) were asked to answer the questionnaires in the study. Findings revealed a significant relationship between BAS Reward Responsiveness and the three factors of aggression which are hostility (r =.188, p < 0.05), disobedience (r=.285, p < 0.01) and destructiveness (r=.318, p < 0.01). Furthermore, results showed that the Behavioral Activation System was a predictor of aggression. This implies that the more rewards the player perceived, the more they become inclined to achieve the goal of the game. The inclination results to being hostile towards the enemy team, disobeying teammates in order to gain more gold for one’s self, and destructiveness which is displayed when they inflict harm on themselves or blame themselves after losing a game.