Counter System X is an enemy in Final Fantasy IV: The After Years exclusive to Final Fantasy IV: The Complete Collection. It is part of the superboss Lost Babil, and is faced in the third part of the battle alongside Defense System Ψ and Control System Ω. The Counter Systems are the three nodes in the front.
Every turn the three Counter Systems will use Laser Barrage, each doing approximately 1000 damage to the entire party. For this reason they should be killed first. They have low HP and will fall quickly.