10 Weapon of ChoiceScore a kill with every handheld weapon (excluding Rocket Launcher and Spartan Laser)
100 ImmuneFinish a co-op mission without becoming infected
100 OverachieverEarn all co-op medals at least once
100 The Enemy of my FriendGet a higher individual score than your partner on all co-op missions
20 ArcheologyComplete Operation F
20 Brute ForceFinish the objectives using only the Brute Shot, melee and grenades in Operation D, Mission 1
20 Escort ServiceKeep all Wolverines intact in Operation A, Mission 3
20 EvacuatedComplete Operation D
20 Extra CreditComplete 75 challenges
20 Foot SoldierFinish the objective without using any vehicles/turrets in Operation E, Mission 4
20 Never Knew What Hit ThemKill a convoy target with every stationary gun in Operation C, Mission 3
20 Nowhere to HidePrevent all Jackals from regenerating their shield in Operation B, Mission 3
20 OverrunComplete Operation A
20 Pension PlanEarn 25,000 Spartan Points throughout your career
20 Powered by MJOLNIRUse every ability at least once (excluding Overshield and Seeker Drone)
20 ProdigyEarn your first Gold star in an operation mission
20 RecruitEarn a star of any type in an operation mission
20 SilvertipDestroy all Mega Turrets with the Grizzly tank in Operation F, Mission 2
20 Skull ComboComplete any mission with the maximum number of Skulls active
20 Switched OffComplete Operation C
20 Switched OnComplete Operation B
20 TerminatedComplete Operation E
20 The Company of StrangersComplete a co-op mission with at least 5 different players
30 Distinguished ServiceEarn all medals in the game at least once
30 Vidmaster ChallengeComplete Operation 5, Mission 1 with the Hollow and Black Eye Skulls active
30 Vidmaster Challenge 2.0Complete Operation F, Mission 4 with the Blind and Thunderstorm Skulls active
40 117Earn all Gold stars in all operation missions
60 Dynamic DuoEarn all Gold stars in all co-op missions
60 ExterminationKill 10,000 enemies in co-op
60 FloodedComplete all co-op missions