Complex sentence: Ventress attacks both Anakin Skywalker and his apprentice Ahsoka Tano, and when Obi-Wan Kenobi arrives as backup, he resumes their battle with her; she flees after he nearly defeats her.
Split into simpler sentences: Ventress attacks both Anakin Skywalker and his apprentice Ahsoka Tano. When Obi-Wan Kenobi arrives as backup, he resumes their battle with her but she flees after he nearly defeats her.