Death Card Pt. 1

Thunder

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.