Tom Clancy's Splinter Cell: Pandora Tomorrow HD

First off you can only achieve this trophy in Missions 2, 5, 6 and 7. Throughout these missions, you are allowed no more than 2 alarms otherwise it is mission failed. To gain this trophy you will need to sound 2 alarms and then complete the mission. Furthermore, I do not advise attempting this trophy under Normal, because during missions you at certain points, the game will reduce your alarm count by 1 so make sure you attempt this whilst playing Hard Difficulty. Please see Phantom Strike to see how to sound alarms.

Mission 2: Cryogenic Lab - 2 Alarms Walkthrough
1. After the brains cutscene, go to the freezer area and make the turret shoot the guy in the room or kill him yourself (now you have ALARM 1). Now deactivate and shoot out the lights in the room and collect the satchel from him which should contain 2 Sticky Shockers.

2. Go to the catwalk, use the shockers on them (much easier than killing) then hide their bodies somewhere dark.

3. Now backtrack through the brain room and head back out to the reception area. There was two guards here, hopefully you have dealt with them, if not do so and head back down the stairs. Halfway down there will be camera, make it spot you and you will then have ALARM 2.

4. Complete the level.