After you go through the swamp, you reach Midoro Palace.
Enter the Palace
When you get to Midoro Palace, try hitting the Iron Knuckle statue at the entrance to see if it gives you a magic jar. It might spit out a red Iron Knuckle instead. If that happens, you should be able to exit and go back into the palace to try again. Once you get a magic jar, you can use the life spell to heal up, then refill your magic with the magic jar.
Go down the elevator, but go past the first floor. Get off of the elevator at the second floor that you reach, where there are ropes spitting rocks nearby.
Go to the left and make your way past the Ropes and Bubble. In the next room, kill the Bot that jumps down from the bricks, then go left and fight the two blue Stalfos (remember to run out of the way if it jumps). At the end of this room, hit the key with your sword to collect it.
Now go back to the elevator and go down one floor. Go to the right and kill the Bots, but be careful of the statue that is spitting blue energy at you. To the right, there are a couple of Mace Demons, and beyond them is another key.
Return to the elevator and this time go up to the first floor, where there are red dripping things in the ceiling. Go to the left and fight a Blue Stalfos. In the next room, there are some Bots and some flying statue heads. Use the downward thrust when jumping over the statue heads to help protect yourself from them. On the way, there is a door that you will unlock.
The next room is kind of tricky. First, kill the Bots that you can see, waiting for them to jump down to you. Then jump past the dripping thing and jump up onto the bricks and collect the key. There is another Bot up ahead, so wait for it to throw itself into the lava before jumping over. Go to the edge of the ledge where the red thing is dripping, and wait for the next Bot to jump into the lava. Then, carefully jump over the gap right after a drip falls. Then jump down and go to the next room.
Kill the Bot near the dripping thing, then kill the Orange Iron Knuckle past the dripper. There is a second Orange Iron Knuckle after the first, and a Bubble, so kill it carefully.
In the next room, there's a red potion bottle hidden in the statue on the wall, but you might need the Jump spell to reach it. Farther ahead there are a couple of Bubbles bouncing around. Go down the elevator.
In the next room you will see a Rope on the right. Walk to the left and fight the Blue Stalfos and Rope, then unlock the door.
In the next room, there is a 500 point P-Bag, but there are also a bunch of falling blocks. You have no way to break the blocks, so you could get trapped between them and have to wait until you die to get out. For that reason, you should run to the next room and come back later.
In the next room, the Iron Knuckle statue above the entrance hides a magic jar, so use the Jump spell to reach it if you need to. Kill the Bot ahead, then carefully fight the Red Iron Knuckle past the dripping thing. Up ahead, there is another red Iron Knuckle and a locked door. Beyond the locked door is the Handy Glove, which lets you break bricks with your sword.
Return to the previous room. If there are two bricks on top of each other and you break the lower brick, the top brick will just float there. You can take advantage of this to wait for the bricks to stack up and then cut a safe tunnel under them. Or you can just run across to the next room.
When you get back to the elevator, go down. There is a Moa in this room that will float past and drop flames at you. The flames will still harm you even when they start to flicker and disappear, so be careful. There are two Orange Iron Knuckles in this room.
In the next room, there is a Blue Stalfos and a couple of statue heads spitting blue energy at you. Carefully kill the Stalfos and break the bricks on the right side of the room. There will be another Stalfos and statues spitting at you. Break the bricks to the right, and there is a third area of Blue Stalfos and statues spitting at you.
In the next room you will find some Bubbles bouncing around. There is an elevator here, and some Bots and dripping things, but go past them.
In the next room, you will encounter a Bot and some Tinsuits. After that, there is a Mace Demon guarding a key. Kill the demon and get the key, then return to the elevator and go down.
To the right, there is a Bot and a Mace Demon on some steps. When you make it past them, there are some disappearing bridges over some lava, and the lower level has a 100 point P-Bag. Take it if you dare, and then head to the right. There will be Tinsuits, and a Red Iron Knuckle near the end of the room.
In the next room, kill the Blue Stalfos and unlock the door beyond it, then kill the Orange Iron Knuckle and finally the Red Iron Knuckle. Up ahead is the boss of Midoro Palace: Helmethead.
Helmethead's head is its vulnerable point. When you hit it with your sword, the helmet will fly off and start spitting blue energy balls at you. A new head will grow in its place and you have to knock that one off. Then that second head will float around spitting energy at you. After two helmets are flying around, the damage that you do to Helmethead will reduce its life meter. At this point you can jump and hit Helmethead's head repeatedly or you can use the downward thrust.
When Helmethead is gone, get the key and go to the right. Walk past the statue to put the crystal in place, then walk through the exit on the right to leave the palace.
Your next destination is the Island Palace.