What happens in the game Halo 2?

master chief gets new armor new weapons come in the pistol loses its scope and this is the first halo game that you play as an elite half the time. mastercheif goes and dose what he usually dose save humanity but now hes out to kill the prophet of the coventet but he only manages to kill the Prophets of regret and the prophet of mercy. and truth survived. so now on to the arbiter he was once a high ranked covenet ship master then striped of his rank due to his failure to stop the demon also known as master chief and became the arbiter.(story of the arbiter. when one has dishonored the convenet he is put as the arbiter which is like a suicide solder he is put into missions to reclaim his honor but the missons are almost impossible so that covers the suicide part. other that the arbiter is rumored to be a great warrior. so the arbiter is sent out on missions to kill traters and others but in the end the entire eliet species is screwed over by the prophets and replaced by brutes. but in the end the elites and humans teamed up and killed the brute leader and worked together to kill him.