Simplify the following text for a Grade 6 native English-speaking person.
Original: As Shang prevents Shan Yu from assassinating the Emperor , Mulan lures the Hun onto the roof where she engages him in single combat . Meanwhile , acting on Mulan 's instructions , Mushu fires a bundle of fireworks rockets at Shan Yu on her signal and apparently kills him .
Simplified: Mulan , Shang and Mushu also send Shan Yu into the storage of fireworks using a cannon .