First load the firefight screen and go to game options. Then go to spartan settings and set starting lives unlimited, max extra lives 50 and then enter base traits. Enter shields and health change to (in order going down) invulnerable, 4x order shields, 200% faster, 200% faster, enabled, enabled.

Enter weapons and damage and change (also from order down) 300%, 300% (change your weapons and starting equipment at will), then change greanade count to 4x each. Change ammo to bottomless clip and weapon pickup enabled and equipment to unlimited.

If uyo want change speed, jump height, sensors and appearance at will.

The credits should roll in with the amout of kills you will be getting (if you did it right). Also, this only works on normal firefight.