[b]The Flood[/b] -would need to kill their food source (all sentient life) to stop them -parasitic and turn their victims to more flood -can use any weapon and probably most vehicles -grave mind can manipulate people into helping the flood before trying to kill them -forunners had to make Halo array to stop the flood (halo array kills sentient life) -don't take a ship to where they are, they will try taking it over