Destroy the helicopter using frag grenades in 'The Only Easy Day... Was Yesterday'.

Destroy 10 choppers using the Javelin Launcher in 'Of Their Own Accord'.

Kill 20 enemies in a row while driving a vehicle.

Kill 5 enemies in a row using 5 different weapons or attachments.

Complete any mission but 'S.S.D.D.' and 'Endgame' without reloading weapons or using melee attacks.

Kill an enemy with the impact damage from a frag grenade to the head.

Run The Pit in 'S.S.D.D.' and finish with a final time under 30 seconds.

Ring the red bell in both rooms and survive the attack.

Complete the single player campaign on Hardened or Veteran difficulty.

Complete the single player campaign on any difficulty.

Complete the mission in the airplane graveyard.

Complete 'Of Their Own Accord', 'Second Sun', and 'Whiskey Hotel' on Veteran difficulty.

Kill 2 rappelling enemies in a row before they land on their feet.