Death Cards

Mission: Semper Fi (Eight of Hearts)
Effect: Headshots cause enemies to explode
Location: At the very beginning after leaving the shack, you will see another shack to the right. The card is inside.
Hard Headed

Mission: Little Resistance (Four of Clubs)
Effect: Enemies take less bullet damage
Location: At the end of the mission before going into the last building, look to the right. The card is in a corner of bushes.
Suicide King

Mission: Hard Landing (King of Hearts)
Effect: Fire explosive pistol rounds while downed
Location: About halfway through the mission you will see a big building with a mini-trench outside. Enter the building, and go into the lower level. The card is to the right when you go into the room with the stairs.
Cold Dead Hands

Mission: Vendetta (Five of Diamonds)
Effect: Enemies take their weapons with them to the grave
Location: After the sniper section at the first part of the mission, Reznov will lead you through a building. Follow the bar around to the end to find the card.
Sticks & Stones

Mission: Their Land, Their Blood (Joker)
Effect: Your weapon arsenal consists of a knife and rocks
Location: Destroy the tanks, and go through the barn. Search the stalls to your right to find the card.
Vampire

Mission: Burn 'em Out (Queen of Hearts)
Effect: Can only recharge your health by getting kills
Location: Just before the second mortar position is a bunker to the left. The card is inside.
Flak Jacket

Mission: Relentless (Nine of Diamonds)
Effect: Enemies take less explosive damage
Location: At the end of the mission, take either the left or right path. Eventually the paths will reconnect. The card is about halfway down the path.
Body Armor

Mission: Ring of Steel (Jack of Spades)
Effect: Enemies die by headshot only
Location: Enter the asylum, the immediately go to the left. The card is in the far bottom left corner.
Undead Soldier

Mission: Eviction (Ace of Spades)
Effect: Enemies come back from the dead
Location: During the first half of the mission, just after the kitchen area, you will eventually see a room to your right that has a large hole in it. Drop down to find the card.
Painkiller

Mission: Blowtorch & Corkscrew (Ten of Clubs)
Effect: Shoot downed Co-op teammates to revive them
Location: Go to the left as you move toward the second bunker. A Japanese soldier hanging upside down is near the card.
Berserker

Mission: Breaking Point (Three of Diamonds)
Effect: Get three kills in five seconds to become Berserk
Location: Clear all four mortar pits, then go to the small shack in the south of this area. The card is inside.
Paintball

Mission: Heart of the Reich (Six of Clubs)
Effect: Paintball guns
Location: The card is in the closed-off subway entrance across the street from the start of the mission.
Victory

Mission: Downfall (Two of Spades)
Effect: Limits your HUD, turns on friendly fire, and bleed out in half the time
Location: Before you get to the theater, some of your allies will break through a door to your right. The card is past that door.

Brilliant work mate, Didn't understand these. I'll take another look next time im on.