Here is the Walkthrough for Arrival.
Welcome, players. This is a walkthrough for the level "Arrival" on Mythic difficulty in Halo 3, the shortest and easiest level in Halo history. Even on Mythic it is, comparatively, a piece of cake. Still, if you are a noob, or have not beaten the game on legendary, then you are strongly advised to leave now. The very visage of this page for unprepared players has been known to burn out the average player's eyes and destroy their spine.
So, let's get started, then?
Remember that nice cutscene you used to have here?
Y'see, if you've beaten Halo 2 on Mythic, this will not be a surprise to you. The Master Chief, in the Mythic ending of Halo 2, was forced to jump out of the Forerunner Dreadnought covering himself with a dead elite instead of a sheet of reinforced Forerunner armoured plating. Therefore, you have to watch in first person (Albeit with full control over the camera) as the chief's shields are burned away by intense heat, his armour cracks and disintegrates, and he is badly scratched by the branches of trees on his way down.
You also have to avoid multiple Covenant A-A batteries that have been set up in the area, requiring a ten minute minigame to be completed.
Once this has been done, you will be treated to a short cutscene where a badly disfigured Master Chief has water poured all over him by a Grunt Minor, who has been eating your marine allies in your absence. You must then battle this grunt in an intense fistfight. You probably won't win, but whatever.
If you do, a Covenant Supercarrier will appear overhead and attempt to deploy several dozen Hunters on you. Since you have no armour or shielding, you can't take any hits. You also have no weaponry. That means you will have to avoid all of their Fuel Rod Cannon shots and melee them to death with your fists. Kill them all and try to glitch yourself up the cliff, as the supercarrier will then glass the area.
End of level, well done.
Next level: Sierra 117