Halo 3 - Killing all Marines on Crow's Nest/Legendary difficulty 

Halo RU-vidr "The Act Man" did a video in which he attempted to kill all the marines on legendary. So I tried it as well and completed it. I left the Arbiter standing there as he onehits you and "killing" him doesnt actually do anything as he just gets up a few seconds later. He is not a marine, too, but Johnson is , and I "killed" him twice.
Act Man's video: • Trying to Kill All Mar...