You can get this achievement through natural progression of the campaign, but it can easily be obtained during Act 2 - Chapter 3: Plan B. When you reach a section where they ask you to choose between two paths (left or right), choose the left path. After spawning, there will be enemies in front of you with some bales of hay being held by a wooden gate. Shoot this wood to release the hay and kill the enemies. Then, look across the river/creek and do the same on the other side to kill a total of 4-5 enemies. Reload the last checkpoint and repeat this process until you get the "Gone With The Windflare" achievement. You can take turns if you are playing in co-op.