A good commander knows how to wield her forces effectively.
To wield your forces effectively, you must use Parasoul and summoning an Egret Soldier a grand total of 100 times. Each Egret Soldier special move has its own special effect whenever you call them out. The following are the 3 Egret Soldier moves you can use for the achievement and the directions below are assuming your character is on the Left side of the screen. All of these must be charged by holding the direction away from the opponent first for a few seconds followed by pressing toward and a kick button simultaneously:
Egret Call (Hold ), then + )
Egret Dive (Hold ), then + )
Egret Charge (Hold ), then + )
This will unlock upon summoning an Egret soldier 100 times. The soldier you call out should not matter, this should unlock regardless of whether you use the Egret Call, Dive or Charge 100 times, it all still counts.