This is how I unlocked the Achievement;
Play the (standard) Campaign on Normal. Holding LT & RT 'fires' the Kryll at the CoG - using the RS you can aim them at enemies (almost like bullet-time).
When you gain control of RAAM, ignore his retro-charge and just use this.
You have to work through 3 scenes where you and your team call-up Seeders. Once you get through all 3 the Act ends, and you will earn the achievement.