Task 1: The First Side
To the Twilight Realm
Before you head out to the Mirror Chamber, the location of the warp to the Twilight Realm, search for the heart pieces and Poe souls that you have not collected yet, as you are now equipped to collect most of them. Also, you may want to consider tackling the Cave of Ordeals (if you haven't gotten the Magic Armor, it is recommended that you do so before challenging the Cave of Ordeals).
After you've had enough questing around, warp back to the Mirror Chamber. When the mirror gets reassembled, it opens a passage to the Palace of Twilight, and the guardians of the mirror will reveal Midna's true identity, that she is the Twilight Princess. Once in the Twilight Realm, head to the east side of the palace exterior and open the door. Inside, you'll find some minor enemies and two floating Zant heads. These heads spit magic bullets, so use your Shield Attack to deflect them. When the projectile hits them, they will be stunned long enough for you to destroy them with your sword. Once both heads are gone, you'll get a small key, so grapple up to the door and continue north.
There is a key in a chest on the north end of the next room. On your way to it, you'll walk through a black fog that turns you into a wolf. Use your senses to see through the fog to find another Zant head. By defeating it, you will make another two treasures appear. The one on the floor holds the compass and the one you must grapple to holds an orange rupee. Once you clear the fog, transform back into your human form, grab the small key, and proceed onwards.
In the next chamber, a barrier will surround you once you get into the center of the room and thrust you into a battle with a ghostly Zant figure; Phantom Zant. He phases around the room, appearing in any one place for only a few seconds. As soon as you see the ghost, go straight for it. If you can hit it before it can conjure its minions, you won't have to deal with any of them. Otherwise, it will summon a large group of enemies to attack you. Even then, make Phantom Zant your main target. Phantom Zant will eventually give up, and explode into black fog. However, he's not defeated for good.
Retrieving the First Sol
After you vanquish the Zant ghost, attack the hand statue at the north end of the room. Pick up the white orb, the Sol, lying on the ground and run to the center of the room. Unfortunately, the big hand you took it from is Zant's Hand. The hand will come to life and start chasing you to steal back the Sol, so be quick in following these next few steps. Put the Sol into a slot on the floor to make stairs appear. Leave the Sol, run up the stairs, then turn around and use the Clawshot to retrieve the Sol. If you find the hand getting too close, you can attack it with the Clawshot to stun it. While it can't be destroyed, stunning it will buy you some time.
Head south into the next room. When you are in the middle chamber, place the Sol into the slot to make stairs appear (the Sol will burn away the black fog). Climb the stairs and grapple the Sol from above to retrieve it. If the hand picks it up before you do, use the Clawshot to snatch it back. As you head towards the door, you'll encounter a group of plant enemies. If they grab you, you'll drop the Sol, run past them and leave through the door. Once you're outside, the Sol is safe. Touching the Twili with it will cure their condition, so do so, then place it in one of the two slots in the area's center section.
Task 2: The Second Side
To the Map
Placing the Sol in its slot causes a square platform to appear. Ride it to the west side, then enter the building. In the first room, you'll ride over the fog on glowing blue platforms. To board them, grapple to a point on the wall, then to the point on the ceiling. Push slightly to see below you, then drop onto the platform once it is directly below you. Hop across the platforms, deflect the shots from the Zant head, and proceed to the north end of the room. Once you defeat the head, you'll earn a small key.
In the next room, walk into the black fog to transform into a wolf, turn on your senses, and use Midna's energy attack to take care of a few Shadow Beings. After they are disposed of, destroy the Zant heads that appear. Since they stick out of the fog, you don't need your senses to see them. After they are all gone, a chest with the map will appear. Grapple to the wall from the north end of the room, then grapple to the ceiling. Advance to the treasure chests in the alcoves from there. The map is in the southeastern chest of the four, and the small key in the southwestern chest. The other two contain rupees. After you get the map and key, proceed northwards.
The Second Sol
Your reward for getting all the way up to where you are is another battle with the ghostly Phantom Zant miniboss. Just use the same strategy as before to dispose of him quickly, then grab the Sol. After you bring the Sol to the room's center, you'll have to take on a few more enemies. Dispose of them quickly before the hand comes, then head into the next room. By placing the Sol in the slot in the center of the next room, you'll make a tall structure rise. If you get there while the hand is entering the room, the structure that pops up will block its way. If not, go back to the previous room and try again, as you won't have enough time to get to the top if the hand doesn't get blocked. Grapple to the north end of the room, then to the west. Climb the structure and collect the Sol once you reach the southwest corner, then head south into the next room.
The Light Sword
In the next room, you'll need to float above the fog to get to the exit. Ride the platforms to a tower that houses two dark orbs. They will light up once you get close, creating a sliding platform that will take you to the southern exit. If you fall into the fog, use the Clawshot to stun the hand, then advance to an orb at the north end of the room. Lighting the orb will make a platform appear that will take you back to your starting point. Once you exit the palace, lift the curse from another Twili, then place the Sol in the other central-section slot. The power of the Sols fuse into your Master Sword to create the Light Sword, which can cut through the majority of Zant's shadow creatures in one swipe as well as clear away black fog.
Task 3: To the Top
The Big Key and a Small Key
Before heading to the central section of the palace, you may want to venture back to the east and west sides to retrieve two pieces of heart. Once done, head up to the curtain of black fog in the center, then perform a spin attack to burn it away, allowing you entrance. Once inside, use spin attacks to clear the fog, then place the room's two Sols into the slots on the floor to make stairs appear. The Sols will not burn away the fog until they are in their slots, so put them there before the darkness returns. Climb the stairs, illuminate an orb to create a square platform, and ride it to the northwest corner. Battle some Zant heads for a small key, then perform another spin attack to light three orbs simultaneously. A platform will appear in their center to carry you to a locked door on the third floor.
In the next room, cut through a curtain of fog on the west side, then use the Clawshot to grapple upwards to reach the Big Key. Before you start grappling, however, defeat all the enemies. If you attempt to grapple to the next platform without fighting them, you might get knocked into the abyss. After you collect the key, go to the orbs on the eastern edge and use a spin attack to light them and trigger a platform to lift you to the southern balcony. Defeat the Zant head there, then hit two more orbs to trigger the platform for a ride back to the main section. Defeat the three heads there, then collect the small key that appears as an award.
In the next room, clear the fog away, then light four orbs in the center of it. A platform will lift you. Hop onto the eastern platform from there, then ride it to two more platforms. Hop onto the north one for a ride to the east ledge. Grapple onto the ledge, then jump to another platform and ride it west. Grapple to a spot on the west wall and defeat a Zant head. Look up from the ledge on the west-central platform to find a grappling spot, then grapple to the center of the room. Move down a bit while dangling, then drop to another platform. Ride it to the room's east end to fight another Zant head. Get a small key from a chest, then ride to the door.
In the next room, you'll face a large collection of shadow beings. Each one takes one hit from the Light Sword to defeat, so you should have no trouble taking them all out, then head into the next room, where you will find the real Zant. Before you battle him, however, he will tell you his back story. Listen to it if you wish, or just skip it to head straight into the longest battle as of yet.
Usurper King: Zant
Ready to demonstrate the full intensity of his powers, ZANT has many tricks up his sleeve to outsmart you in battle.
Your fight against Zant takes you on a tour across various locations in Hyrule where you encountered past bosses or minibosses. You'll use a variety of weapons and tools during each phase of the fight, then attack him with the Light Sword. Zant will attack you with rapid fire energy blasts that you can't deflect with a Shield Attack, so just avoid or block the attacks as you prepare for your next attack.
The first part of the fight takes place in the Forest Temple boss arena, where you fought Diababa. Zant hovers over the poisonous liquid, so hit him with the Gale Boomerang to draw him near, then attack with the Light Sword. An easy way to draw him close is to block his rapid fire blasts with your shield, and -target him. Once he stops firing, throw the Gale Boomerang to bring him to shore. After hitting him a few times, you'll reach Stage 2.
The second battle takes place in the Goron Mines, where you fought Dangoro for the Hero's Bow. Zant will warp from place to place along the edge and jump up and down to knock you into the lava. Use the Iron Boots to stay anchored. When Zant starts to attack with the blasts, take off the boots, raise your shield, and run at him. You should get there by the time he stops firing, so hit him with your sword, then return to the center of the disc and repeat until he takes you elsewhere.
This part takes place underwater in the Lakebed Temple, to where you fought Morpheel, so equip the Zora Armor, the Iron Boots, and the Clawshot. Zant will appear from a giant helmet. After the door opens, he will start firing at you. Avoid his shots, then use the Clawshot to draw him to you while you are weighed down with the boots, then proceed to attack with your sword. After you hit Zant a few times, four giant helmets will rise from the ocean. Survey them and watch for the one Zant is in, then repeat the process. Eventually, he will change his location again.
This stage takes you back to Forest Temple, but this time in the room where you fought Ook for the Gale Boomerang. During this stage, Zant will hop among the poles. Approach him while he's firing at you, then hit to slam into his pole twice. That will make him fall to the ground. Run up to him and attack him with a few strong sword swipes, then repeat until he takes you elsewhere.
This time, you find yourself in the Snowpeak Ruins boss arena where you faced Blizzeta. Zant begins this stage as a floating giant. Equip the Ball and Chain and watch his reflection in the ice; keep moving to ensure that he doesn't land on you. Once he drops, hit one of his feet with the ball. He'll shrink and start running, so track him down and hit him with your sword (put the Ball and Chain away first, it weighs you down too much to catch up). After you hit him in his miniature size for a while or if you fail to do so, he gets big again and repeats the process.
For the last segment of the battle, you'll be back outside Hyrule Castle, in an area defined by a magic barrier. In this stage, Zant has three attacks. Two of the attacks are designed to push you into the barrier. While he's flailing around to begin the battle, you'll be able to attack him a few times with ease. Next, he'll spin like a top. Defend yourself with the Shield and keep away from the edges of the arena. After he stops spinning, he'll become dizzy for a few seconds. Hit him with everything that you've got in that time frame. Zant's final attack will have him warping around the arena and attempting to slash you. Run from him and don't let him corner you. After he is done with that attack, he'll do another spinning move. With patience, you'll be able to finally defeat him.
After Zant takes a powerful beating, he returns to his throne. Midna gains back all of the Fused Shadows, but her curse stays in effect. Zant, even though severely injured, proclaims that he will be ressurrected by Ganon forever, and that Midna will always be cursed because of Ganon's power. Eventually, Zant brings Midna's anger out, and she unleashes a killing blow to Zant with the Fused Shadow, making him explode. She realizes how strong she really is, and wishes to confront Ganon.
Now, with the true threat revealed, you can return to Hyrule, but there is a Heart Container up by Zant's empty throne that you can't miss.