Instructions
Play all co-op sessions to completion. Completing co-op missions awards cash; however, quitters do not receive any reward and will lose a significant amount of the cash they've already earned, greatly impeding their ranking progress.
Take out the most heavily armed enemies in "Co-op Arena." A finished "Co-op Arena" match automatically results in a $5,000 cash bonus. Earn additional points and add more money to your win payout by killing enemies with the most advanced weaponry (e.g., GAU-19s and RPG-7 soldiers).
Focus on building your combo meter in "Survival." In this co-op mode, gamers earn points from executing enemies and collecting the treasures they drop. What's more, these actions contribute to a combo meter that multiplies the amount of points players earn, resulting in a bigger cash payout after each completed session.
Reach a combo meter level of 10 in "Survival" to earn an extra cash bonus. The "Killer Combo" medal awards an additional $2,000 each time a player maxes his combo meter to Level 10, allowing a player to rank up even faster at the end of a co-op "Survival" session.
Aggressively pursue treasure in "Gold Rush." This mode differs from "Survival" by awarding point multipliers based solely on the amount of treasure a team collects. Ignore the enemies (if possible) and go straight for the gold before the default x3 multiplier decreases to earn as much points and cash as possible.
Complete a "Co-op Objective" level with two players on the Crushing difficulty to earn the Back to Back and Masters of the Universe medals. Find a partner and set the difficulty to Crushing with the "square" button in the lobby. The challenge involved is steep, but you'll be rewarded with two medals that amount to a $10,000 bonus added to your win payout.