The Last Climb and Descent
You'll emerge outside the Temple. Travel right to the end of the Spirit Tracks, going straight through the junction instead of turning north into the Fire Land. Through here is a Warp Gate. To activate it, shoot the green triangle at the top, then blow the whistle until you pass through. You'll emerge on the other side of the Land, between the Sanctuary and the Tower of Spirits. Go straight there and prepare for the final climb.
Climb to the top of the spiral staircase. Just outside the last door is a blue portal. Step into the light. It will take you to the 23rd floor, just outside the room where you battled Staven/Byrne. Go through the room. Outside, climb the spiral staircase. Get the Stamp from the Stamp Stand here. At the altar you'll see two large eyes. Charge a Light Arrow, and shoot both. A doorway will appear on top of the Altar of the Demon King. Enter. Inside are several pots and bulbs. Break them for health, bombs and arrows. Save your game and go down the stairs...
The Strongholds of Darkness: Tower of Spirits Floors 30-24
Now begins your journey through the final levels of the Tower of Spirits. These floors will test all your skills to the limit and combine the elements of the previous floors, meaning you will run into every Phantom type you've seen in the tower. Fortunately, even though there are no Tears of Light to collect here, you can use the Lokomo Sword to strike Phantoms.
Right now, you can see a Phantom appear in the lava pits of the northeast section of the room, but the first thing you need to do is head down the staircase behind the one you just came down. You'll enter another dark area of the tower, crawling with Phantoms. You can easily sneak behind one now and take have Zelda possess it. Then, head back up to Floor 30.
Now, have Zelda cross the spikes off to the right of the corridor and step on the switch in the safe zone to get through yourself. From here, you'll need to hitch a ride on Zelda's shield and cross the lava while staying out of the phantom's sight, or lure this phantom to one of the safe zones and strike him and have Zelda move to him. Either way, you need to activate two switches in this room at once. Head to the lower one and place a bomb, and then quickly get close enough to the upper one without getting swamped by the Fire Keese and have the Boomerang strike it. This will open the door in the upper-right corner