Complex sentence: Eventually, he manages to pin her down and tries to strangle her, but she catches hold of his machete and swings it, knocking him off her, and brutally hacks him to death, before Joel arrives and pulls her off.
Split into simpler sentences: Eventually, he manages to pin her down and tries to strangle her. Ellie manages to catch hold of his machete and swings it, knocking him off her, and brutally hacks him to death, before Joel arrives and pulls her off.