Complex sentence: Bonzo takes out these frustrations on Ender and as a supposed punishment, he forces Ender to do desk work when his army is practicing, and only allows him to participate in battles after 4 minutes, however, Ender is forbidden from firing his gun.
Split into simpler sentences: Bonzo takes out these frustrations on Ender and as a supposed punishment, he forces Ender to do desk work when his army is practicing. He also prevents Ender from participating in battles until after 4 minutes have elapsed, and, even then, Ender is forbidden from firing his gun.