Step 1: Daily Challenge must be one that says a certain amount of kills and any game mode on Reach

Step 2: Go into Firefight(not matchmaking)

Step 3: Edit guns to what you want and make yourself invincible (also make everything all grunts for easier kills)

Step 4: Pick a map of your choice

Step 5: Start up game

Step 6: Get every kill except for one (example: if challenge is 400 kills then get 399)

Step 7: Pause game and end it

Step 8: Start game back up

Step 9: Get one kill and you have the challenge

Step 10: When you fervent kill pause the game, then disconnect your router and wait till it says your disconnected, then plug it back in.

Step 11: Get another kill and repeat step 9 until the credit limit us reached

Thankbthe topic and +rep