Eren's death in the manga was a powerful moment. It was brought about by a combination of his own decisions, the opposition he faced, and the overall plot developments. It left a lasting impression on readers.
Eren managed to beat Annie through a combination of his determination, newfound powers, and strategic thinking. He exploited her weaknesses and caught her off guard.
Well, it all happened when Eren got hold of that special serum. When he used it, it activated a genetic trait within him, allowing him to transform into a Titan. It was a crucial moment in the story that changed everything for him.