I beat legendary a few times. it was much easier the first time once I beat cairo station. I also found out that halo1 legendary is almost a piece of cake.
i've got to oracle then it went hard(those little bastards can be hard if their many)
ok, halo 2 and 1 are very, very easy to beat on legendary, the only way you can possibly die is if you cant even get head shots on the sniper jackals, otherwise just use needlers and snipers, simple if you get overwhelmed toss a grenade 5 feet in fornt of you and run, shooting backwards like its happy hour in vegas