Start this area by climbing the nearby wall and keep going until you start moving along the ceiling. Hit the stalagtites with your blades to break them. Not too far along this path, some Cursed Wretches will spawn and likely sit back and spit at you. Quickly move up and attack them until they fall. Drop down at the end and open the Red Orb Chest.
You should see a grapple point on the ceiling now, so press Circle to latch on and jump to the second one. Jump off to the other side and climb the ledges, following the path until you get to the Caldera. Go to the center platform and you'll face off against some Fire Harpies, who will continually divebomb into the ground.
After defeating all of the harpies, jump across to the other side and continue along the path. There is a cracked wall ahead that you can't do nothing to yet, so ignore it and find the blue/green chest and a save point. Save and continue on until you can drop down.
There's another door here that requires a gear to open, so keep going through the next door. Follow this long path to Thera and do the quick QTE to gain Thera's Bane. As you head back to the previous room, Thera will collapse the floor behind you, so quickly move.
Here, The Keeper will sic one of the statues on you, called an Automaton. It will swing its gear horizontally, as well as do a vertical smash with it. If too close, it will just to do a stomp and if too far, it will charge at you. You need to attack it with Thera's Bane active, which is done by holding R1. However, this consumes the fire gauge underneath your magic one, but it replenishes over time.
The Caldera
Once you've caused enough damage, press Circle to initiate a short QTE where you mash Circle to finish off the Automaton. This will net you a gear item that you can use to open the door you saw when you dropped down into this room. So, go over there and put the gear on the door and mash Circle to open it.
In the next room, open the chest for a Gorgon's Eye and read the book nearby. You need to use Thera's Bane on the gears to destroy them, creating a platform to allow you to jump across to an area you visited previously. Go forward and hold Circle and press R1 when prompted to break open the cracked wall you saw earlier.
Grab the health if you need it and open the Red Orb Chest, then continue on the path ahead. At the end, drop down onto the slide and jump at the end to an area where you need to fight two Minotaurs, as well as a couple of Fire Harpies. After finishing them all off, grab the health if you need it and pull the lever all the way to the left.
This will cause some water to spill into the lava and form a rock platform. Jump onto it and ride it, fighting off some Cursed Wretches (just continually grab them for instant kills). When you see a wall you can climb, quickly jump onto it and go up to find a chest with a Minotaur Horn and a save point.
Sidle along the ledge and use Thera's Bane to destroy the gears there. Jump to the next ledge and keep moving until you spot green and blue chests, as well as another cracked wall like before. Open it and grab the Red Orb Chest and then sidle into the crevice nearby.
Volcano Core
Keep going into the Volcano Core and not even 5 seconds into the area, Scylla attacks you. Press the button that appears to latch onto Scylla, where you can mash the Circle button to continually attack her. There will be another quick QTE like the last one, then more mashing the Circle button.
At the end, you'll have to rotate the left analog stick to impale Scylla and put her down for good. With that out of the way, get onto the nearby climbable wall and go down to find a ledge with two chests and some Cursed Wretches. Kill them and open the chests for some red orbs and another Gorgon Eye (should be enough to extend your life bar now).
Climb to the top and use the grapples points to get to another ledge and upon climbing to another ledge, a chain of events will occur. You'll be dropped onto a slide and when you reach the bottom, you will jump onto a climbable wall. Hurry up this one or the lava will get you and you will die.
At the top, jump to another ledge that will start falling when you land on it, then get to another ledge and one more grapple point. You'll land on another climbable wall, only you'll have to watch out for falling rocks while climbing. When you see one coming, jump to the other side and keep doing this until you get to the top, where you'll see a cutscene and start the next area.
