Complex sentence: In the end, Chris and his comrades discover how the nightmare began and witness the death of Albert Wesker, who was betraying them all along, and they face and kill a prototype Tyrant released by Wesker.
Split into simpler sentences: In the end, Chris and his comrades discover how the incident began, and witness the death of Albert Wesker, who was betraying them all along. They also face and kill a prototype Tyrant released by Wesker.