Get the Bomb Bag
Go across the lava and onto the platform that is shaped like a snake's head. As you approach the soft soil to the right, red chuchus come out. Kill them, then dig the soil to reveal an air geyser. Float up the air to get 20 rupees.
Go across the platforms to find fire keese and the mogma from earlier. His partner is missing. He saw Zelda getting dragged away. Don't dig the soil on the left because a red chuchu is hiding there.
Go back across the snake platform and go up the stairs. Wait for the two rising platforms to fall, then go across.
There are two gear ropes on each side. Cut them with your sword. There is another gear rope on the right side of the door. Launch your beetle at it to cut it. Go through the door.
You will encounter your first Lizalfos up ahead. Fi will tell you to target it and press down to call her and get her advice. She will say that its arm guard will block your sword, so you have to pay attention to which angle is required to hit the lizalfos.
There are some crumbled rocks in the lava up ahead. There are bomb flowers on the rocks, so launch your beetle and hit a bomb with it to set it off and make the rocks explode. A large stone ball will roll over to you. Jump onto the ball and use the control stick to roll around. If you start to fall off, just stop moving. You will automatically center yourself on the top of the rolling rock whenever you stop.
Roll over to the area on the left where a platform is rising and falling on the lava. Throw a bomb onto the platform when it goes down, then it will explode on the rocks, allowing you to reach a chest that contains a golden skull.
Now roll to the ledge on the southeast side of the room. There is a mogma here who asks you to bring his bomb bag back. Its on the other side of the rocks. Crawl into the hole in the cage on the left and kill the bokoblin in here. Then roll a bomb through the small hole to break the rocks.
Go through the door that you revealed beyond the rocks. Two Lizalfos will attack you. Try to get the lizalfos away from each other so you only have to fight one at a time. Remember to swing the sword in the direction that isn't blocked by the arm guard. When each one dies, it might leave behind a lizard tail, so be sure to collect those. When they are gone, open the chest that appears. It contains the bomb bag.
Leave the room and Ledd will talk to you. Tell Ledd that his friend is worried. Ledd will give you his bomb bag. Go toward the rolling rock and Ledd will give you some bombs. You can also put bomb flowers into your bag. Just pick up the bomb flower and press B. You can crawl into the cage that you went into earlier and fill up your bag with the bomb flowers in there.
Get the Map
Roll over to the center platform where there is a bird statue. Walk to the west side of the room where a cracked rock is blocking you on the ledge. Throw a bomb onto the cracked rock to get rid of it. Jump across and kill the lizalfos, then go through the door.
Jump over and kill the bokoblin. There are Magma Spumes in the lava that spit flames at you. You can kill them by throwing a bomb at them. Go to the side of the room and jump onto the rising platform when it falls. Kill the three bokoblins and open the chest above to get the dungeon map. Don't miss the spot of soft soil behind the chest.
Get the Dragon Sculpture
Now go back to the room with the rolling rock. Roll under the bridge on the west side of the room. Stop at the ledge with the chest on it to receive a Blue Bird Feather. Then go to the bridge that points north. There is a part that sticks out and has a target on it like the one on your rolling rock. Roll the rock into the part that sticks out to push it in. When you are done, part of the bridge will rise.
Now go to the right side of the room, just north of the cage. Look past the first Magma Spume in the lava to see a crack in the wall. Throw two bombs at it to break open a hole in the wall.
Avoid the lava spouts and go through this passage. There is a barrier with a bokoblin standing on it, but there is a crack in the wall to the left that you can bomb twice to create a new hole in the wall. Go through it and continue along the passage to reach a big red door. Use your beetle to cut the gear rope on top. Then launch your beetle again and send it through the passage beyond the bird statue to reach the other side of the red door, where there is another gear rope. Cut it to open the door.
Roll through and stop at the end of the passageway to reach the bird statue that your beetle flew past a moment ago.
Get back onto the rolling rock and wait for the lava spout to stop pouring, then go past. Carefully roll across the narrow lava bridge and kill the fire keese at the other side.
Kill the lizalfos on the ledge to get 20 rupees from the chest. Then roll over to the bridge that points north. There is another thing sticking out that has a target symbol on it. Roll into it with the rolling rock to make the bridge go up the rest of the way. If the bridge isn't high enough for you to reach the door in the north wall, it means that you didn't push the thing sticking out on the other side of the bridge, so you will have to roll back to the center of the room and go under the bridge on the west side to reach the other side of the bridge and push the thing in.
Now that you have raised the bridge, go through the north door.
Jump across and run up the slope. As you run, some boulders will roll down from the ceiling. Look for the gap in the rocks on the left side and run through it.. Then run to the gap in the wall on the left to wait for your stamina to refill. Then run to the top of the slope.
Let your stamina refill, then crawl through the hole in the fence on the other side. Dig open the air geyser on the right and float up to the stairs that go up the side of the room. There is a ledge at the top and you can see some rocks in the wall across the way. Look to the right and you will see a scratch in the bricks of the slope. Throw a bomb at that scratch or just above it. If timed correctly, the bomb will explode on the rocks in the left wall.
After you break the rocks, go back down the stairs and run up the slope to the gap that you just opened in the left side. After your stamina refills, run up to the top of the slope.
In the next area, you will notice the boss door behind the huge lava spout. Save at the bird statue. Go up the winding narrow stairs and walk up the slope (no need to run.) At the top, you will find the Dragon Sculpture.
Open the Boss Door
When you go back the way you came, a giant boulder will come out of the dragon's mouth. Hold the A button to run down the slope, then run onto the stairs to the side of the slope as soon as you can. If that boulder hits you, you will die and get a game over screen, so be quick.
After the boulder passes by, it will go into the lava spout and stop the lava from flowing.
Go to the boss door and use the dragon sculpture on it. Remember to look at the image of the Wii Remote that shows up when you hold the A button. Rotate your Wii Remote as if you are holding the dragon sculpture. When you have matched the shape, the lock will start glowing and you can put the sculpture into the lock. Go into the boss door.
Go up the stairs and you will see a boulder rolling through some ribs. Walk to the chain on the floor and Fi will say that Zelda was probably chained there, but she escaped and continued along the path.
Go up the slope and Ghirahim will appear. He will say that a female servant of the goddess took Zelda away. He says that he needs to use Zelda in order to resurrect his master. Then he will summon Scaldera.
If you need hearts or bombs during this battle, go up to the top of the slope.
To defeat Scaldera, back away from it when it walks up the slope, then throw a bomb at it when it opens its mouth while chasing you. Run down to follow it when it rolls down to the bottom of the slope.
After it rolls to the bottom of the slope, it will open its mouth and take a deep breath. Quickly throw a bomb so that it sucks the bomb in. If you wait too long, it will start spitting fireballs at you that you will need to sidestep. If you manage to throw the bomb into its mouth when it takes a deep breath, some of the rocks on its body will crack and you will be able to see its eye. Hit the eye with the sword as many times as you can.
After hitting its eye many times, Scaldera will flare up and start chasing you up the slope. Run away until it stops burning, because it moves too quickly for you to just walk away. When it stops burning, slowly back away and throw a bomb at it when it opens its mouth. It will roll down again and you will have to throw a bomb into its mouth when it takes a deep breath. Hit its eye when it appears.
Near the end of the battle, Scaldera will stand up tall on its legs while chasing you. It will move too quickly to outrun at this point, so run under it and wait for it to roll back down. Stay on the side to avoid it when it rolls toward you. Then throw a bomb when it takes a deep breath and hit its eye repeatedly to defeat it.
Get the Amber Tablet
After the battle, get the heart container and refill your bomb bag. Then go to the top of the slope and go through the door with the glowing crest on it.
Inside, you will see a cut scene. After that, use a skyward strike on the crest to get the Amber Tablet. Fi will say that you are destined to go to Lanayru Desert and use the Gate of Time to go to a distant world.
Use the bird statue outside to the left to return to Skyloft.