How to unlock: You have to hit an enemy with Charge attack while cloaked (single-player mode).
This is one of the easiest trophies to acquire, even though the description says otherwise. First things first, equip your character with two abilities - Tactical Cloak from the Tech tree and Charge from the Biotic tree.
Now you have to look for an enemy - regardless of whether he's protected with a shield and/or armor. Once you have one, activate the Tactical Cloak ability, aim at the enemy and use the Charge ability to attack him. If your character reaches the enemy and deals damage, you will get the trophy. If not, repeat the whole process.