This is an unmissable campaign progress achievement. If all goes well, you will unlock it during the same combat mission where you use the skulljack on an Advent officer and unlock
After you hack the officer, a new enemy called a codex will appear. This enemy has the ability to clone itself. You must kill all of the codices and then complete any remaining objectives for that mission. After you have done so and earned a success for that mission, the achievement will unlock.