Go into the Sealed Grounds and go up to the Gate of Time. When you charge up your sword for a skyward strike, the seal on the Imprisoned will fail again. Go outside.
Groose has created the Groosenator. It can go side to side with the control stick, and you can point the Wii Remote to aim.
Go down to the very bottom. When you reach the sealing spike, it will fail and The Imprisoned will come out.
Attack the toes. Eventually it will start climbing the wall. Groose will speak up at this point. Press up on the control pad to use the Groosenator. Hit the Imprisoned anywhere on its body with a bomb to make it stop climbing the wall. After that, kill its remaining toes. If necessary, use more bombs from the Groosenator to stun the Imprisoned again.
When it falls down, hit the sealing spike into its head by slashing your sword upward at the spike.
The Imprisoned will get back up. Hit it with another bomb when the Groosenator is ready. This will make it stop moving temporarily, so kill its toes again, using more bombs if necessary to stun it. Remember that once all of the toes on a foot are gone, that foot will no longer send out shockwaves when it stomps. When The Imprisoned falls, hit the spike into its head a second time.
It will glow red and slither up the slope. Use the groosenator to stop it, then kill the toes and hit the spike into its head a third time. The spike will go back down to the pit, so go down to it and follow the on screen instructions to slash your sword in the proper pattern and seal the spike.
Open the Gate of Time
Go into the Sealed Grounds and hit the Gate of Time with a Skyward Strike. Go through. After a cut scene, go through the door as Impa says.
Zelda is there, and she explains the situation. You obtain the power to claim the Triforce, and your sword is powered up into its final form.
Afterward, talk to Impa, then go back through the Gate of Time to reach your own time. The old woman tells you that the Triforce is hidden in Skyloft somewhere.
Groose has decided not to return to Skyloft. He asks you to plant saplings.
Find Clues to the Triforce's Location
Go back to Skyloft. Talk to Headmaster Gaepora. He doesn't know where the Triforce is, but as you leave, he tells you that Levias, the sky spirit of Skyloft, would know how to find it. Levias is said to be trapped in the Thunderhead. Gaepora asked Professor Owlan to find out more, so go to Owlan's office, which is next door to Headmaster Gaepora's room.
Owlan says that Levias seems posessed. The two of you go outside, and Owlan tests you on the Spiral Charge. Run off of the pier and call your bird. Use the spiral charge to break the 10 targets in under 120 seconds.
After you have succeeded, Owlan says to ask the owner of the Lumpy Pumpkin for information about how to approach Levias.
The owner makes a batch of pumpkin soup in a huge basin to take to Levias. Scrapper will be summoned to carry the basin. The owner says to land on the island with the rainbow.
Fly to the Thunderhead and land on the island with the rainbow. The possessed Levias will attack.
Run off of the platform and call your bird. Use a Spin Charge to kill all of the eyes on Levias's sides. Kill any of the flying monsters that come near.
After you have destroyed all of the eyes, fly over the flat part of Levias's head and dive off of your bird to land on the flat part. Run to the parasite in the head.
The eye parasite spits out green spiky things. You can hit these back toward Bilocyte with your sword. Do an upward slash to the left and right to knock the green things into the frills on the sides of Bilocyte's head. Then hit one of the green things straight up to hit Bilocyte's eye. Bilocyte will fall down, so don't let it land on you. Then run over and hit the eye repeatedly with your sword. After a while, Bilocyte will move to the side after spitting the green things, so you will have to hit it upward but to the side in the proper direction. Repeat the strategy until Bilocyte is defeated.
Talk to Levias
Levias will return to normal and tell you about the Song of the Hero. This song is the key to finding the Triforce. Levias knows one part of the song, and the three dragons know the other parts. Levias tells you to come back to him after you learn the other three parts, and he will sing the entire song for you.