In Chapter 1 Prisons. Combine 3 achievements. Vampire, Eagle Eye and Reload Mash. At the point in the game where a pop up tells you about Commanders, you will be on a catwalk approaching a commander on the ground. Jump down and Stealth Kill him, he drops a pistol, pick it up and fire 9 rounds into the wall/ground, then use the last bullet to kill the guard on the lower level to the left. Reload checkpoint and repeat.