I would almost consider this story related. You get this pretty late in the game. It's a power that enables you to dash/fly towards in enemy while you are in mid air. After you gain this power, while in mid air, hit
. You will instantly kill the enemy. There are a lot of times you have to use this power to finish an area. You must get this in story mode, as it is not available elsewhere. The Power of Flight can be used on enemies that are walking on the ground too, as long as you have enough distance in between when you jump.