Get on top of the staircase to meet the Smith God, Hephaestus. You will have a scene here where Kratos will look for the Flame of Olympus. Unfortunately, the smith god doesn’t know so let’s proceed.
Head over to your left to find a lever to pull and a save point. Once you pull the lever, you will open a door out of this forge. Go down to the staircase and go back to Realm of Hades.
Now you will be in a circle where the Stone Statues you just fought are standing still. In the middle you will see a crank where you can turn it around. Do it and stop on the first door you see on the right. Prepare yourself to fight some hounds. To get started with the Obedience School Trophy, kick these hounds instead of killing them with your blade. Once they have all been defeated, open the chests.
Now go back to the circle platform again and turn the crank around, this time to the rubble covering the wall. Use the Bow of Apollo to get it out of the way and proceed to the Realm of Hades.
On your way back to where you started, you will have a scene with the blue girl in flame seeking for your help. After the scene, you will get the Blade of Olympus, in which you use it when you fill the Rage of the Gods’ meter.
With the Bow of Apollo you just received, you can now enter the Palace of Hades. After burning the rubble that covers Hades’ Palace, you will be fighting two Cerberus that spit out fire.
The best way in taking out these Cerberus dogs is through rolling and spamming it with Kratos’ Blade of Exile once you see a free spot. You will have to take out each of the three heads. You might find it hard to fight if you’re playing on Titan mode. Be patient because it will take a while. Do a lot of rolling!