The Final Battle
Video Walk-through
The Colossus is lined up to fight you for the last time...in a manner of speaking. In order to take him out, however, you'll have to charge and use the Blade of Olympus, which lies in the middle of the platform on which you will reside while fighting the Colossus. Doing so will require you to grab the Blade and charge it with the R1 button, but when you attempt to do so, the Colossus will knock you away.
The Colossus has three major attacks here, the first being a rift attack where he'll ram his shorn arm against the ground and cause numerous grooves to appear, which will quickly turn blue with energy. These are fairly easy to avoid. In addition, there's a hand slam that will come down whenever you're near the Blade of Olympus. You can double jump over the shockwave, but that's easiest to do if you're standing on the bottom side of the Blade. Lastly, if you get close to the upper edge of the screen, the Colossus will knock you around with a two-sided sweep of the arm and an arm slam into the ground.
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Begin here by getting close to the discarded hand on the ground and using R1 to slam it into the Colossus' head. This will stun it momentarily, allowing you to run up to the Blade and press R1 again to load it up with all the red orbs that you've obtained. The Colossus will reanimate shortly afterward and begin slamming you again.
The next item you'll have to charge the Blade with will be your magic meter, so stand just below the Blade, double-jump over the fist slams, and use Poseidon's Rage to damage the fist. (You can also just stand right under where the fist comes down and use Poseidon's Rage just before it hits to damage the arm and avoid damage yourself.) After the beast is stunned again, charge up the Blade with your magic.
Lastly, you have to charge the Blade with your health. Stunning the Colossus can be a simple matter of double-jumping over the fist slam shockwave and hitting the fist once or twice, or you can get closer to the Colossus's waist and hit it up close. Either way, it will eventually be stunned again, allowing you to charge up the Blade completely and wrest it out of the guide.
The Blade of Olympus
With the Blade in your hands, charge up to the Colossus and start whacking away at it, staying close to the fist of its right arm as it rests on the ground. The left arm will periodically sweep the area with low-damage energy blasts, so try to roll out to the right of the screen to avoid the brunt of them. When you deal enough damage to the Colossus' arm, it will withdraw, allowing you to hit it with an animated attack to bust through its weak spot and enter its interior portion.
Colossus Interior
Start making your way up through the interior of the Colossus, keeping in mind that the blue-shrouded pieces of wood will greatly wound you if you touch them. After jumping over a blue beam that lies in your way, walk towards the central pillar of the structure and press R1 to drain the energy of the Colossus into the Blade. Doing so will reveal some netting on the nearby wall, which will allow you to proceed upward. Find the rope bridge that leads across the area and drop down on the far side by tapping R1.
After climbing up a bit more, cross a beam to find another area where you have to drain the central pillar. (A health chest is near the wall to your left here, somewhat out of sight.) Drain it and walk back across the beams to move on. At the top of the netting, you'll have to grab onto the ledge in front of you and shimmy around to the left, using R1 to drop down and go hand over hand to avoid the jutting, burning wood. Before attacking the chains around the central pillar and draining it, note the netting off to your left; your first Eye of Gorgon lies atop it.
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When you drain the third set of wood, a chain will drop down. Climb it to reach the giant's head. Climb the ladder when you reach it and flip the switch nearby to drop the large metal object here down to the ground. Climb back down the ladder and strike the metal with your sword to start it swinging, then climb the ladder again and flip the switch one more time to retract the object; it will now swing back and forth and block the energy beams that go to the Colossus' eyes. When it blocks the energy beam closest to you, use the X button while hanging from the rope to quickly get to the middle of the rope. Repeat the process to get to the far side of the rope, then drop down and find the final set of energy-imbued wood and destroy it.
With that done, the Colossus is dead and will begin falling. Quickly hop from platform to platform to reach the mouth and exit the giant once and for all.
The Wrath of Olympus
After a lengthy cutscene, you'll have to begin walking towards the Blade of Olympus. You won't reach it, though, as an ominous figure will accost you. You cannot win the fight that you get into, so do your best and enjoy the resulting cutscene.
