Lost Babil is a Superboss in Final Fantasy IV: The After Years exclusive to Final Fantasy IV: The Complete Collection. It is fought in the Final Tale by speaking to Challengingway in the tail collector's home, and paying a 500,000 gil fee. However he can not be challenged until after the game is beaten. According to Challengingway, Lost Babil is a prototype of the Giant of Babil that was scrapped after it rampaged out of control.
The player battles Lost Babil by forming three parties. Each party engages a different part of the giant. If the player is victorious, they receive three Silver Apples and two Soma Drops. Lost Babil can be challenged as many times as the player wishes, as long as they can pay Challengingway's entry fee.
The first party the player forms faces Giant's Torso and Giant's Right Arm. The second party fights Giant's Chest, Giant's Left Arm and Giant's Head. The third party battles Defense System Ψ, Counter System X and Control System Ω.