Single Player: Stealth kill a Ceph Stalker [Bronze / 15G]
Location: Mission 2 You will encounter Ceph Stalkers for the first time in mission 2. Just a few minutes after entering the underground area, you will enter a room with tall gras and a cutscene will begin to play. Go down the stairs and stay away from the gras. Activate the cloak ability and stand still until a Ceph Stalker is close to you. Sneak up from behind and hit R3 (PS3) / RS (X360) to perform the stealth kill. Move quietly so that the stalker doesn't hear you.