Vanquish

Only on Act 3-7: Phantoms

Work your way to the top of the Kreon. After having fought an "unknown" morphing enemy for the second time, you will take an elevator to the very top of the Kreon and be back outside. Walk to the yellowish thing at the back, which will trigger a cutscene showing the Kreon's energy conduit and Sam saying something about destroying it. Once you gain control of Sam again, do not destroy the energy conduit just yet!

Instead, go behind it, and you will find a gun turret manned by a red robot. Kill the bot, then use the gun turret. There are plenty of red enemy transport ships flying around. You must destroy at least 5 of these to get this achievement. As soon you've destroyed the 5th one, the achievement unlocks.