: Save all your flashbangs and frag grenades specifically for this room.
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 call-of-duty-ghosts
: Earned by collecting all 18 Rorke Files scattered throughout the campaign. : Save all your flashbangs and frag grenades
: Do not enter the room immediately. Stay behind the doorway for cover. call-of-duty-ghosts
To unlock this achievement (Gold Trophy / 100 Gamer Score), you must clear the common room in on Veteran difficulty without taking any damage.