Requires you to win Sandstalker 10 times. This minigame is first played in the intervention quest "The Five Cogna Lords: Figaro" during Chapter 21. Minigames can be replayed at any time either by repeating the intervention quest or accessing the minigames menu of the console in the Twins' Bedroom at Nine Wood Hills. Playing it via the Twins' Bedroom is advised as there is no dialogue or fights to skip through.
Controls/Rules:
This is a turn based strategy game using a 5x5 grid;
You have three characters: Terra [L], Shelke [M] and Vivi [S];
Your HP is shown below your characters and if it hits 0 on any character you will lose it;
Lose all 3 characters and it's game over;
On your turn you can either "move" in any cardinal direction or "attack" any adjacent square;
If there is a cogna in the square you attacked it will lose 1 HP;
If you miss by one square you will see the word "Resist" and a silhouette of the cogna;
Cogna can spawn in the same square you placed your characters on;
The cogna follow the exact same rules as you do.
Tips and Tricks:
Try to find a good starting position where you are able to cover the most ground, a diagonal line in the centre 3x3 grid seems to work best;
It's best to use Terra or Shelke for attacking as Vivi will be killed off too quickly if discovered;
If you hit a cogna first it will usually move;
The game will tell you how many spaces a cogna moved and in what direction, use this to loop it into moving again and again until you have killed it;
If a cogna hits you first and it has more remaining HP than turns required to kill off your character it will continue attacking you no matter what, either move or sacrifice your character to learn its position;
If you're ever in a stale mate and know where your last cogna is but can't risk moving just keep attacking the same square and it will eventually move.
Credit to Eternal_Rach