Instructions
Place the "Halo: Reach" DVD in your Xbox 360 to launch the game. Select "Firefight" from the main menu.
Open the "Game Options" menu and select "Spartan Settings."
Select the "Base Traits" menu and activate the "Shields And Health" option. Choose "Invulnerable" under "Damage Resistance."
Choose "Legendary" under "Difficulty."
Select "Start game." Walk towards enemies and let them inflict damage to your character. With the game options that you selected, the enemies are able to damage you but not kill you. Every attack increases the number of points in your account. Continue letting enemies attack you until you have amassed the desired number of points.