In matchmaking select the score attack playlist once in keep selecting "None of the Above" until you get Gruntapocalypse on Corvette The important thing here is stay alive for your sprees and try and group the together for Multikills If done correctly I have heard of up to 11,000 credits per game Not as effective as the ONI: Swordbase way and not nearly as quick but this method can't be tapped out from overuse. Also this method can also be very boring and you will hit the 60,000 credits limit in just over an hour Don't forget the +rep if I helped.