Descend through the area, avoiding shots from distant cannons and taking care of enemies that are positioned on the left and right of the platforms the ladders link. When your each the bottom, destroy a crumbling block along the right side of the shaft to reveal a doorway, which you should enter.
You can obtain the Spear ability from a guard who patrols here, as you head to the right. You'll see a pad that fires a rocket to the point you indicate. This chamber is lined by such rocket pads, and in the background there are brown blocks at regular intervals, always near enough that you can hit them from the various launcher pads. Take care of the blocks as you head right, avoiding enemies and spikes. When you reach the far right after destroying the various brown blocks, you can find a 3D Warpstar that takes you to the backdrop. Then you should run along it, first dipping into a recess to hit a switch, then working your way left to find a Key. Continue left from there, avoiding hazards, until you reach the far left side of the area and pass through a locked gate. Along the way, you can pick up a Keychain. Your reward when you reach the far left side is a 1up, but you can hit a bomb block to the left to produce a passage. Follow it to reach a Sun Stone. Then return right and head through the doorway along the upper ledge.
In the new chamber, you'll have to head to the right while watching the backdrop. A huge wall rotates around, and it'll do some damage if you don't position yourself within openings. As you advance right, you'll have to float up to ledges and avoid enemies, but it's fairly simple if you're paying attention. When you reach the right side, you can pass through a doorway.
Now you are advancing through an area where there are bomb blocks suspended in the air. If you hit these, they will produce stone ledges you can run along. In the background, cannons fire and their shots reach the foreground. Avoid them as you work your way right (you can fly if you prefer). Near the far right side, you'll notice an Archer enemy standing on some ledges. Absorb him, and to the upper right there's a bomb block in the ceiling. Another of the blocks is hanging in the air nearby. It will produce a ledge that comes up shy of the overhead block. You can stand on it and fire an arrow upward to produce an explosion that reveals a secret door. Pass through it.
In this new room, there's a simple archery puzzle. From where you appear, aim at the target floating to the upper right. Then tilt your handheld to produce a shaft through which the arrow can pass (by turning the wheel at the center of the area). A new target will appear to the lower right, so climb the ladder and fire a second arrow toward that target, after adjusting the positioning of the shaft. You'll cause the obstruction to fall out of the way, and you can head right for a Sun Stone. Then exit through the nearby doorway.
You will find yourself back in the main corridor with the cannons and bomb blocks. As you head right, shoot another block to reveal a Keychain, and proceed right from there to reach a door. Through that door, you'll find another of the rotating walls. As you head along here, you can find a Spear enemy to inhale, but you also need to pay close attention to the wall. Some of the apparent openings are just paintings and won't spare you from harm. Near the right side of the area, you can hit a bomb block to reveal a Keychain. Further right, you'll find a glowing doorway, floating above the floor. Before you enter it, look to the right. You can destroy a portion of the wall there to reveal a cranny, with the Rare Keychain: Marx Soul resting inside. Grab it, then enter the door.
The next corridor soon leads to some Miracle Fruit. Grab it and keep advancing right to arrive at a platform situated in lava. There is a drill attached to the right edge of that platform. Stand on it, then face left and use Hypernova to suck at the metal fan blade. That will propel the platform slowly across the lava, drilling anything in the way. You still have to watch that you don't pass through an active eruption of lava, however, and there's a four-way spinning arm of lava that you have to rush under when the time is right. To the right from there, you can ride a 3D Warpstar into the backdrop, then reach twin waterfalls of lava. Stop when Kirby is positioned directly between the two of them, then jump in the air and float upward to find a Sun Stone. Then drop back down and continue right. You'll reach another 3D Warpstar. Ride it into the foreground, then continue your advance on yet another of the drill platforms. You'll have to advance through a double set of the four-way arms, and then drill at the base of a head-shaped statue to force it open so that you can pass through and enter a door.
Now you are ahead of a confrontation with some red dragons. As you head to the right, you'll reach a platform and the dragons will fly in to assault you. They circle around you, heavy shields raised. You should wait for one to pause to the left or right, lower its shield, and toss a rock at you. Grab it with Heavy Nova, then let the dragons start circling again. Fire the rock as the dragon with its lowered shield is lining up with the platform to send it flying toward a distant volcano. You'll have to repeat that process three more times, until all of the dragons are done for. They move faster each time, and the fourth one will spew flames that you need to steer clear of before it fires a rock at you (just stick to the side of the ledge opposite the dragon when it pauses).
Once the last of the dragons are gone, the volcano will spew out a bunch of junk, including the final Sun Stone in the stage. It also deposits the goal door on the platform where you're standing. How convenient!
