Complex sentence: Dante joins Vergil's group to oppose Mundus, eventually taking him down and freeing humanity from the demons; however, Vergil's intentions to take Mundus' place cause a fight between the brothers which Dante wins and Vergil escapes.
Split into simpler sentences: Dante joins Vergil's group to oppose Mundus, eventually taking him down and freeing humanity from the demons. However, Vergil's intentions to take Mundus' place cause a fight between the brothers which Dante wins and Vergil escapes.