Thanks A Killion (20)
Kill 20,000 enemies or players

Just go to the mission 343 Guilty Spark in Halo:CE and take yourself and get a assault rifle to the part where you first encounter the flood area.


Now you just have to shoot the infection forms with the assault rifle as they come out the doors. When they open the door that you first entered the room from, kill most of the infection forms then press start and select last checkpoint. This will put you back to the checkpoint before the infection forms knocked down the doors.
Using this method will help you rack up 1000's fast asap.