Siegecraft Commander

Easy to obtain on the third level once you reach the open middle section. Line up your trebuchet to shoot the outpost attached to the ballista and the barrage on the opposite side. This can be linked with Booster Shot if you are the maximum distance away from the outpost. Could take a couple tries due to the enemy airships that will flood that area.

I made a video for this achievement if you'd like to see it on video!

(2:10)