Complex sentence: Under the influence of Ego's power, Quill helps him activate the seedlings, which begin to consume every world, but Quill fights back when Ego reveals that he killed Meredith due to the distraction she posed.
Split into simpler sentences: Under the influence of Ego's power, Quill helps him activate the seedlings, which begin to consume every world. However, Quill fights back when Ego reveals that he caused Meredith's death due to the distraction she posed.