This study analyzes the role of prosumers -users who are both consumers and producers- in the transmedia advertising narrative of the video game "League of Legends", one of the most popular worldwide. Using a qualitative approach with phenomenological design, we explored the experiences and perceptions of 15 active fan-gamers in their communities. The findings indicate that prosumers not only consume content, but also generate their own material and disseminate it on platforms, acting as key influencers in the expansion of the game's narrative. This phenomenon facilitates an ongoing dialogue in communities, promoting co-creation and dissemination of content without expecting direct compensation from developers. This study highlights the need for brands to recognize these contributions in their advertising and marketing strategies. We reveal how active prosumer integration can influence t...