Again, take the north corridor, but don't pick up any new shadowbombs this time, just wall-run. Make sure to bounce off the right wall not just to avoid falling down into the abyss, but also to grab a Boatman Coin.
Your destination is a chamber with a new statue and an active lantern. Begin by rotating the statue west to unlock a way to a secret shown on the above screen, which is a Book of the Dead page ([The Book of the Dead] side quest).
Go back to the statute and this time rotate it south to unlock the passage shown on the above screen. Head south and carefully explore the area under the large drawbridge to find a chest and a Soul Arbiter's Scroll.
Keep going south and then turn west to find the lantern shown above. Be cautious because after lifting it off the pressure plate you'll be attacked by Skeletons. Put the lantern down for a while and take care of the enemies.
Afterwards, pick the lantern up again and take it to the chamber with the statue. There, face east and put it on the pressure plate seen on the above screen.
You now need to go back to the first statue with the active lantern, so once again take the north corridor and wall-run. When you get to the first statue, turn west and use Death Grip to grab the lantern you've left there earlier (the above screen).
Take the lantern to the statue and rotate it left so that it unlocked the passage to the south corridor again. When you do it, pick up the lantern and go down that corridor. As you may be guessing, you need to get to the inactive statute you've passed by earlier (the above screen) and place the lantern on it.
You can now cross the lowered drawbridge (the above screen), go west and reach a new demolished staircase.
Same as before, wall-run when needed while going up the staircase. I recommend being on a lookout for a hidden Relic of Etu-Goth on the way (the [Lost Relics] side quest). Continue down to the lower floors until you reach the basement level.
I strongly recommend bashing all the objects in that area. A group of Skeletons will show up as a result, and the reward for taking them down is a large chest (the above screen) which is hiding a particularly valuable treasure. Once you take it, move into the adjoining cavern.
The second Stone will also be heavily guarded, so get into a battle with Scarabs and Skeletal Archers. I strongly recommend taking down the Archers first, given that their attacks deal a lot of damage and there's no effective way of hiding from them. Of course, use Death Grip as often as you can, rendering the targeted Archers virtually defenseless against your offensive.
Keep fighting until every enemy is down and only then approach the altar to take the second Animus Stone. Once you have it, go through the newly unlocked passageway. Since it's an armory (the above screen) I suggest smashing every object you see because there's a high chance you'll find a lot of rare and valuable items.
Move to the adjoining chamber and look around for a chest first. Then, grab onto the ledge seen on the above screen and examine both balconies for a Boatman Coin.
Go back down and start climbing where shown on the screen, using Death Grip when necessary. Once you're up, turn around and grab onto a new handhold to get to another chest. After examining it, return to the opposite balcony and use the switch.
Same as before, approach the altar and use Death Grip to place the second Stone on it. You now have only one Stone left to find. Go back to the upper balconies and take the north door shown on the above screen.
As soon as you enter the new chamber, a battle with Skeletons, Skeletal Warriors and Skeletal Champions will start (watch out especially for the latter). Use special attacks, but most of all keep in mind that Death Grip can also be used to throw the Champions off balance, making them easy targets for subsequent attacks (the above screen). Winning this battle is not so difficult as it may seem.
Afterwards, examine the area thoroughly to pick up treasures and then enter the adjoining chamber. Ignore the lowered drawbridge and turn right. Move past subsequent chambers until encountering Skeletons, Skeletal Warriors and Skeletal Champions in the last one.
After getting rid of the first group, you'll be swarmed by Skeletons popping out of walls. Since they have little resistance and the room you're fighting in is quite small, I recommend using Harvest or any other area-effect attack.
Again, pick up treasures and move to the adjoining chamber. Begin by standing on the pressure plate shown on the above screen. Wait until the drawbridge is raised and use Death Grip to catch the shadowbomb seen in the distance.
Move to where the screen shows, which is near the throne. Throw the shadowbomb at the right switch. This will cause the whole structure to rotate and make it possible for you to enter a new area. Approach the third altar and prepare for a battle.
You'll be facing a mini-boss called a Scarab Hulk. Its basic (though not the only one) attack is a jump that makes shock waves on contact with the ground, and when that happens make sure you maintain a safe distance. Apart from that, watch out for the upper legs, though they're much easier to dodge.
I recommend attacking the Scarab right after each jump, using Death Grip to get close to it in an instant. What I don't recommend is using the Reaper Form just yet - will be much more useful in the approaching boss battle.
Keep hitting the Scarab until you empty his health bar. Afterwards, pick up whatever treasures he dropped and approach the altar to take the third and the last Animus Stone.
Go back near the throne. Use the left switch and quickly run to the throne so that it rotated with you. You now need to go back to the central part of the Gilded Arena, so head south. When you're there, jump down to the arena and place the last Stone on the altar the same way as before. Get ready for the boss battle.