"Kill 4 guards in one kill streak" is an optional mission objective in Sequence 7 / Memory 02: The Gunpowder Plot
Walkthrough[edit]
As you approach each of the Restricted Zones where the Gunpowder is stored, you will find no shortage of guards around them. Engage a number of Soldiers and Scouts in a fight. It will make the quickest work for you.
Careful use of the Dart Gun can make this a lot easier as you can Berserk the Brutes and Captains since they interrupt kill streaks. When you emerge from the tunnel on the far side, where you found the Gunpowder Keg, you will find a good location to get the kill streak. The gunpowder keg to the West is also a good location as there are 4 guards in front of it, facing North.
