Wow, come on people. I did this for the 360, but I'm sure it's the same on any system.
Step 1:
Find another person who is as ambitious as you to do 1v1 Cage match.
Step 2:
Set up your killstreaks/classes on what you need (The point is to finish as many challenges as possible) What I did was Care Package - Sentry Gun (I'll explain later) - Emergency airdrop. For classes, you choose whatever you want, but you need a Tactical Insertion. I always chose the Stinger as secondary (I'll explain this later too).
Step 3:
As your friend 'searches' for a Cage match, you should be in your friends list watching his name. When you're able to "Join Session in Progress" do it as quickly as possible and you'll join his game, and BAM, you're now fighting against your friend.
Step 4:
I always preferred private chat, vs in-game talk, just so there was never a break. Meet up with your friend at a certain point in the map, I like open 'run-way' areas for the Emergency Airdrop. At this point, you decide who is going to shoot first.
Step 5:
Assuming you shoot first, shoot your buddy in the face, call him a bitch, and tell him to put out his Tac again (These are the ways of the Internet). Rinse, repeat. Once you hit your 8 killstreak (Or 7 if you are working on a Hardline challenge), throw out all your packages and ask your friend to kill you to reset your killstreak.
Once you hit 18 kills (20 is game winning) you should be at 900 points, now it's your friends turn. He kills till he hits his emergency, you reset him (You're at 950 now) and then once he hits 950, you both decide who gets game winning. This is also prime time to get the 'dropping crates' challenge.
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Small Variations:
You can always work out the details as you progress, but this is the basics. Care Packages help you finish up stupid challenges like "Call in 100 UAVs" and crap.
Sentry guns are good way of Riot Shield boosting, but also give your friend 200 points for them disabling them. Super easy to set one up, facing away from him obviously, as he throws down his Tac. After him stabbing it, you go back to shooting.
Stinger is my launcher of choice. During the massive amount of care packages you'll get, sometimes you'll be faced with Harrier Strikes, or Attack Helicopters, or even just shooting down UAVs for a quick 100 points. You can get more points against Harriers and Choppers if you let them kill you first. This can get problematic if you friend is already at 950, or if you just suck ass with the Stinger.
- Side Note on this subject, Pavelows can be annoying as well sometimes, so it's best to save that one for last, and while your friend calls it in to get credit, you can finish the game up with the last kill (Or Vise-Versa).
Throwing in new killstreaks means you need to adjust how many you go to before you reset. I was doing the EMP challenge and would go to 14 kills (Hardline on), my friend would kill me, and I would finish up the rest of the kills to snag another care package.
You can also create a new Gamertag specifically for boosting other people up, so they're K/D ratio goes up. I have one that's called ISuckAtMWtwo, his W/L ratio is like .02 or something, it's great. Feel free to add him I'll help you out and show you the ropes if it's still confusing to you.
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I highly doubt this way of 'working around the system' hasn't been posted here before, that's why I'm not making a new thread. Just trying to help these people out here.
This is a very effective way of boosting and not being banned. There are other ways, such as taking up a full Free-For-All match, or Domination, but this is definitely the easiest. I boosted up 2 Prestige's in a day.
I'm not boosting my guy anymore, I just didn't like the first Prestige emblem, I'm keeping my real GT legit, but I have extras that I **** around with and welcome anyone who needs help. Thanks to Red Stripe (lucsky8 here on the forums) I know how to do Elevators too, so I can help with that as well. I only have a 360, so sorry to the others.
Thank / +Rep if If you found this educational or not, either to you or others.