: Earned in Mission 6: "Legends Never Die" by killing 6 enemies with a knife while underwater. Call of Duty Ghosts: Piece of Cake Trophy/Achievement - HTG
: Your teammates are invincible; let them push forward and finish off any stragglers while you stay safely behind. call-of-duty-ghosts
If you are looking for other "pieces" of the game's completion requirements, you might also be interested in: : Earned in Mission 6: "Legends Never Die"
To unlock this achievement (Gold Trophy / 100 Gamer Score), you must clear the common room in on Veteran difficulty without taking any damage. : Do not enter the room immediately
: Do not enter the room immediately. Stay behind the doorway for cover.
The phrase "provide an piece" regarding most likely refers to the "Piece of Cake" achievement/trophy, which is earned by completing a specific objective during the campaign . "Piece of Cake" Achievement Guide
: Earned by collecting all 18 Rorke Files scattered throughout the campaign.