Metal Gear Solid 4: Guns of the Patriots

Missable The FROGs Soldier Unit is the boss you will face during Act 1: Liquid Sun. See the spoilers below as it is part of the story.

The encounter will initiate after you have met with the Rat Patrol Team 01 in Advent Palace. You must defeat them non-lethally. This means that you must deplete their Psyche bar and not their Health bar. The Psyche bar is the small, thin line below the Health.

During Act 1: Liquid Sun in the Advent Palace, you will fight the FROG Unit for the first time. These enemies leap all over the place and are very skilled with CQC so be very careful when you approach them. The Mk. II Gun is your best bet for this fight. On lower difficulties, the battle won’t be as hard. When you start the fight, go to the right wall and get non-lethal equipment, especially Stun Grenades and Sleep Gas Mines. From this point, you can run towards the enemy FROGs and knock them out with CQC or simply shoot them with the Mk. II. If they hang from the ceiling and they are pretty high from the ground, they will fall down and their health goes down. Strangely this doesn't count as kill. To be on the safe side, shoot them while not hanging. When you take the first of them out, more will appear. Take them out and quickly go downstairs. Equip a Stun Grenade and get ready to throw it at incoming enemies. Take out the remaining FROGs with the Mk. II gun. When the FROGs jump on the walls, take cover behind the wall before the doorway and take out the FROGs as they show up. When you reach the kitchen, you can throw a Smoke Grenade to stun the enemies for a while. Next, simply go to the bath and wait for the team. When the wall collapses, stun the rest FROGs. After the cutscene, throw a Smoke Grenade where the bulldozer will be and stun the rest.

After the fight, you will find yourself in a garage where you can find the doll.