NOTE: As of the latest patch (1.03), this glitch still works; I completed a few rounds last night after installing the update and received the credits.
Once you have everything set up properly and a decent team of 4 infiltrators (or 3 Infiltrators and 1 Engineer), you can earn $40-45K credits every 4-8 minutes. If you are interested, please read on:
NOTE: This is a glitch but, it's not a gimme. You will need to be fairly comfortable with the game to pull it off so I don't suggest this for the ME3 MP newb. This can be done with 2 players but, 4 players are highly recommended.
Quarian Infiltrator (Cloak , Hack ) x2-3 - Depending on the setup you choose, 1 could serve as distraction and medic with the Engineer while the other 2 complete the objective(s) for the wave.
Salarian Engineer (Decoy ) x1-2 - This guy will be responsible for creating a distraction for the enemies. Be prepared to die but, stick it out as long as possible
Step 1: (15-20 minutes)
Set up a new private match with the following options (these are the options we used and are confirmed - others may work as well?):
Map: Firebase White
Send your invites to get your players into the lobby. At this point, you may choose whatever character class/race you desire and play normally until you get to Wave 10. Once you are in Wave 10, you must complete the objective. After you complete the objective, let everybody on the team die. Yes, you read that correctly... die. This will result in a Failure screen however, you will have been rewarded your credits for completing the 3 objectives of that challenge.
There are a few options for the objective. You will either have Targets to assassinate, a Single-Point Hack, or a 4-Point Hack. I have bolded the 4-Point Hack because this is the fastest/easiest to complete IMO and requires no extra equipment/resources. You can attempt any of these but, I would recommend you start over with Bronze and play through until Wave 10 again until you get the 4-Point Hack objective.
Now here comes the interesting part...
Step 2: (1-3 minutes)
Once everybody is back to the lobby, the Leader (Host) must change the difficulty to Gold. Everyone else should now pick their designated role(s) for the farming that is about to commence. See the Recommended Team section above^.
Don't worry about your weapons as you won't really be needing/using them. You want to have the fastest cooldowns possible for Cloak and Hack. Don't equip Weapon/Armor enhancement equipment either as you will just waste it.
Start the match.
Step 3: (3-5 minutes)
Now it makes the most sense to have everyone playing on each others' Friends List for invitation purposes. As soon as the Leader (Host) gains control, immediately exit by pressing and Quit Match. This will force the server to migrate to another person in the party as the New Leader and the Wave will restart. All other players simply allow this to happen and DON'T push the circle button!
1 or more of the other players should immediately invite the person that left the match. That person should be able to make it back into the match a minute or 2 later. Now simply complete the objective (hopefully just deactivating the 4 stations) with your Infiltrators while utilizing Cloak. Your Engineer should be throwing out the decoy and attacking the primary forces of the Geth to draw their attention. Once you have completed the objective, you will see the Credits awarded and all 4 players must then die. You will get the fail screen again but, all Credits will be awarded to all players in the match, regardless of when they joined in (even in the last 30 seconds for the previous host that left the game).
Step 4: (Repeat)
There is a new host and you may want to reassign the role(s) of the team based on who will be leaving and returning to the match but, that's it. Once everything is all set up you can earn up to $45,000 every 4-8 minutes.
Edited by bmj14772, 30 August 2012 - 02:08 PM.