"Papa" dies in the desert after being shot down by military forces while trying to save Eleven (at the end of Episode 8/start of 9). 🔓 The Ending Explained
Max lures Vecna into her mind at the Creel House while Lucas and Erica watch over her. Stranger Things - Season 4Eps9
Vecna reveals he discovered the "shadow" particles in the Upside Down and shaped them into the Mind Flayer to act as his tool. "Papa" dies in the desert after being shot
In a heroic turn, Eddie refuses to run and stays behind to lure the bats away from Dustin. He dies in Dustin’s arms, finally proving to himself he isn't a coward. In a heroic turn, Eddie refuses to run
Despite the team's efforts, Vecna technically wins the battle. Because Max died (even briefly), the fourth gate opened, causing a massive "earthquake" that tore through Hawkins.