After awakening the Wind Sage, Link must bring her to the heart of the Earth Temple and defeat the monster that drains the Master Sword's power.

Get Medli's Figurine if you Haven't Already
Nintendo Gallery Note: If you haven't gotten a figurine of Medli yet, it's best to do so now, because if you wait until after you complete the Earth Temple, you will have to go back to the Boss Room to find Medli again.
Get the Map
Press A when next to Medli to pick her up. Then jump across to the other ledge. Medli will help you by flapping her wings. Pick Medli up and go through the door. Be sure to carry her through doors or you will leave her behind. You can set her down with R or throw her by pressing A.
Press R to put Medli down, then go defeat the Moblins. Then pick Medli up and climb the stairs to the left. She will talk to you. Go to the top of the stairs, then keep holding Medli and jump to the next platform, which has a switch on it. Put Medli down, stand on the switch, then while standing on the switch, play the Command Melody. When you're Medli, you can tap A to fly for a short time. The meter at the top left tells you how much longer you can fly. Be aware that Medli does NOT jump if she runs off of ledges. She will just fall, and she can't fly while falling. She has to be standing on solid ground before she can start flying.
As Medli, fly over to the next platform and step on the switch to open the bars, then have her hop off of the platform. Take her to the next room.
Put her down, then go around the room to make Chuchus appear. You can defeat the Red Chuchus and Green Chuchus with your sword, but to defeat the Black Chuchus, you need to lure them into the beam of light in the middle of the room to make them turn to stone. Then you can either smash them with your Skull Hammer, or pick them up and throw them to break them. After you have defeated all the Chuchus in the room, the bars will open. Use a fire arrow to burn the lid off of the warp jar, which is in the northeast corner of the room. Then shoot the banners on the walls with a fire arrow to reveal a Joy Pendant and five rupees. Use the Boomerang to get them.
Play the Command Melody to switch to Medli, and walk into the beam of light. Press A to shine the light from your harp, and press B to put the harp away. Face the weird outline of a chest in the north part of the room, then illuminate it with the harp for a few seconds to make it solidify. Then turn around and face the other wall, and shine light on the two statues by the wall to get some items. Switch to Link, open the chest to get the Map, and pick up the items that appeared from the statues, then pick up Medli and go to the next room.
Get the Compass
There are no enemies in this room, so walk down the stairs (if you accidentally fly, be sure to press A to land before you hit the fog) and carry Medli into the light to the right, put her down, and play the Command Melody to switch to her. Shine the harp light into the fog below to create a path to a post that you can hit with the Skull Hammer. While Medli is aiming the harp properly, press R to switch back to Link, and Medli will still be shining the harp light where you had her point the harp. Follow the path that she cut through the fog. If the fog touches you, you can't use weapons or items for a while, so do your best to avoid it. Use the Skull Hammer on the post. Then pick Medli up and take her through the door that just opened.
Put Medli down. Defeat the Bubbles that come out of the coffins. Then, go toward the back of the room and look to the left for a ladder. Climb up, and pull the block until the light appears. Play the Command Melody to switch to Medli, and use the light to make that chest turn real, but before you open it, walk Medli to the corner of the room next to the door that you came through. It's the only door without bars. As Link, open the chest to get a key. Floormasters appear. The floormaster near the chest will only grab Medli, not you, so keep her away from it. If the floormaster does get her, return to the room where Medli shined the light into the fog. She will be up in a cage above the door. You can just switch to her and have her fly out. Defeat the Link-grabbing floormaster by the door near Medli, then pick up Medli and go through the door.
Carrying Medli, go straight and go through the locked door.
Put Medli down and go around the room defeating the Red and Green Chuchus that appear. To defeat the black ones, you need to use a Fire Arrow to burn down the banner on the west wall that has some light shining through. Stand in the light, wait for the chuchus to turn to stone, then put one on each of the two switches. Hurry up those stairs before the stone chuchus start moving again, ignore the chuchus that appear behind you, and push the block over the edge onto the ledge below. Defeat the chuchus, then play the Command Melody and switch to Medli. Fly up to the door above. As Link, climb up to the ledge. Pick Medli up and go through the door.
Drop Medli and defeat the floormaster. Push the nearest block all the way to the left until it falls into place, and an opening will appear in the ceiling, creating a beam of light. As Medli, stand in the light and face the little yellow symbols on the walls. Shine the harp light on a symbol until that piece of wall crumbles. Do this for all the wall symbols. There are two on each side for a total of four. Then shine the light on the big statue on top of the block until it crumbles. As Link, push the two blocks as far as they will go. Climb up and get the compass from the chest. As your boat explains, now that you have the compass you can always see Medli's location on the dungeon map. Press up on the D-pad, not the D-stick, to look at the dungeon map. Look for her on the map if you ever get separated. She appears as a purple circle.
Get a Key
Switch to Medli, fly up to Link, and switch back to Link. Break the jar and catch the fairies in bottles if you wish, then pick Medli up and go through the door.
Drop Medli. Go up and defeat the moblins while avoiding the poes. To get rid of the poes, first knock the lantern out of its hand using any of your weapons, then let them possess you. For a while your controls will be backwards, but eventually the poe will leave and die. Once the monsters are gone, ignore the stairs, and switch to Medli. Fly up to the light on the right. Shine the light on the statues on the other side of the room, then walk off of the ledge. As Link, open the chest to get a joy pendant, then pick up Medli and go up the stairs that appeared earlier. Go through the door on the left.
Put Medli down, but don't fall into the pit yet. You can try to use the Deku Leaf to jump and glide on top of the coffin on the right. After the lid falls off, turn to face the ledge that you jumped from, then jump and immediately use the Deku Leaf to glide back to the ledge that you came from, then use the Boomerang to get the key from that coffin. If you fall into the pit, though, you must slowly approach a coffin from the side to make its lid fall off, then run away from the Redead inside. Make sure to only open one coffin at a time so you are only fighting one monster at a time. Stay far back from the Redead, because if you get close to it, it will move slowly toward you and freeze you. You can throw bombs at it to damage it from a distance (it takes three bombs to defeat it), or do a jump attack to hit it before it can freeze you (but it can be difficult to tell the correct distance to jump from), and jump backward afterward to avoid getting frozen. Otherwise, slowly walk close until it freezes you. If you're far enough away, you'll unfreeze in time to defeat it. If not, it will grab you and drain your life. If that happens, just tap buttons and wiggle the D-stick until it lets go, then quickly defeat it with your sword. The other coffins have 10 rupees and a key. After you get the key, climb up the ladder that fell. Take Medli out of the room with you.
Go through the locked door to the left. You will automatically drop Medli.
Stalfos
Get your bombs, boomerang, and skull hammer ready, and walk forward to start the fight with a stalfos. Stand back and throw a bomb at it, making sure that the bomb explodes on it. When it falls apart, stun its head with the boomerang, then smash its head with the hammer. After you defeat the first one, there will be two more. Try to lure them away from each other and fight them one at a time.
Get the Mirror Shield
When they're all gone, go up the stairs and open the chest to get the Mirror Shield. Stand in the light that appears, swing your sword so you're holding a weapon, and hold R to raise your shield. Use the shield to shine the light onto the sun and moon symbol above the door, and the door will open. Go through.
Get Keys and Treasure Chart
Leave Medli where she is and go defeat the monsters in here. You can defeat the poes by making them drop their lanterns and possessing you like before, or you can climb the ladder and shine the light on them to make them turn solid, making them vulnerable to your sword. When the monsters are gone, use the Command Melody to switch to Medli and fly up to the light. Shine it to the middle of the room in a place where Link can stand in it. Keep shining and press R to switch back to Link. Stand in the light and shine it on the symbol on the wall below Medli. You might also be able to crumble the symbol on the right wall of the passage, but you can wait for an easier opportunity in just a moment.
As Medli, go to the end of the new passage and shine light on the statue to make it crumble. If you didn't make the piece of wall in the hallway crumble, have Medli keep shining where the statue was, and switch back to Link. With him, shine the light on the wall symbol to find some rupees. Pick up Medli and go through the door.
Carrying Medli, fly down, being careful not to land in the fog. Carry Medli through the left door (in the south wall).
Put her down and defeat the bubbles and the nearest floormaster. Pick up Medli and keep her away from the other floormaster, which will try to catch her, by waiting for it to go to the left side of the room. Go to the switch to the right. Put Medli on the switch and leave without her through the door that you just opened.
In this room, shine the light onto the symbols to reveal a chest containing a joy pendant. Exit the room.
Medli is standing near the other door, far away from the floormaster that wants to catch her. Pick her up and go through this door to return to the fog room.
As Medli, stand in one of the lights and shine it into the eye of the face until that side of the face turns bright. Keep her shining in that spot and press R to switch to Link. If the face stops shining, switch back to Medli and try again. As Link, get into the other light, get out your shield, and shine it into the other eye until both sides are shining. Take Medli down the stairs and through the door.
Put Medli down and go downstairs. Try not to fall off the edge because it's a long way down. There is a ladder you can climb up if you do fall. The Bubbles over the bridge will affect you with fog, so use your Deku Leaf to blow the fog away, then defeat them. The bridge isn't the safest place to do this, so stand on each of the ledges and lure the nearest bubble to you.
Tingle Tuner Note: In this room, turn on your Tingle Tuner. The question mark here is down the passage to the left and around the corner, so before getting there, use a Tingle Bomb on it. If you are playing The Wind Waker HD on Wii U, you can use a regular bomb on this spot. Then carry Medli to the middle of the bridge, jump with her and fly to the wooden chain platform, then drop her there, being careful not to drop her off the edge. Use the deku leaf to glide to the other platform and to the ledge with the chest. Defeat the red bubble and get the Tingle statue. Glide back to Medli and pick her up. The safest way to get back to the other ledges is to carry Medli and fly right, onto the ledges next to the bridge, then switch to her and have her fly up to the ledge above.
Go get Medli. Put her down next to the big music-note slab, play the Earth God's Lyric, and take Medli through the door.
Drop Medli. You can stun the Redeads by shining light on them. Or you can just throw bombs at them from near the entrance. Defeat them, then shine light on each mirror to make the statues crumble. Then shine the light on the statue straight ahead, then pick up Medli and go through the door that you revealed on the right (in the west wall).
Put Medli down and go down the stairs. There is fog everywhere, as well as floormasters. First, go all the way left, then go north through the fog until you see a floormaster, then go all the way to the east, then go north, then go west to reach the chest, which contains a key. This also removes the fog. Defeat all the floormasters to make a chest appear. It contains treasure chart #20. Pick up Medli and leave the room.
Get the Big Key
Drop Medli and go through the door straight across (in the east wall), leaving Medli behind.
Go to the edge of the ledge until the floormaster's arm comes up. Shoot it with arrows until it is defeated. Run across the fog, avoiding the floormaster at the end, and get up on the ledge. Pull the mirror until it stops. Burn the rightmost banner with a fire arrow to get a Joy Pendant. Use the Skull Hammer on the post to make a beam of light appear, then, standing on the edge of the ledge, defeat the floormaster near you with arrows. Cross the fog and exit.
As Medli, fly up to the locked door. As Link, push the block against the wall to reach Medli. Pick her up and go through the locked door.
Put Medli down and walk all around the room to reveal monsters. Stand in the light and make the poes come to you. They'll turn solid, so defeat them with your sword. When the monsters are gone, switch to Medli. Stand where the light is shining on the brick wall (don't stand near the mesh), then face the side-by-side statues at an angle and shine the light on them to make them crumble. Keep shining at the place where the left statue was. As Link, first get the items that you revealed, then stand in Medli's light and shine the light onto the remaining statue. Get Medli and go through the door.
Drop Medli and use your Boomerang on the keese. First, if you want 20 rupees, go slowly through the east path (making sure not to let the coffin lids fall on you), defeat the Redeads, and take the 20 rupees from the chest at the end. Then go back and go through the north path, defeat the stalfos that comes out of one of the coffins, and make the other coffin lids fall (there aren't any Redeads along this path). Get Medli and bring her to the music-note slab, play the Earth God's Lyric, and take Medli with you through the door.
Take Medli down the stairs and set her down when you reach the big open area. Turn right and use a bomb to open the warp jar. Go down the stairs until you can climb on the vines. Climb right and down to reach the rest of the stairs. Once there, switch to Medli. Have her go down the stairs until she is near the vines, but she can't climb them, so tap A once or twice to fly forward while staying next to the wall. She should land on the platform below. As Link, take Medli down the stairs and through the door.
Put Medli down and switch to her. Fly across to the platform in front of you, and step on the switch. As Link, go down the ladder on the right. There is a mirror near the bottom of the ladder. Slide it along its path until it stops. Switch to Medli, fly to the low platform that is in the path of the light from the mirror, face northwest, and use the harp light to make the statue crumble. Then face southwest and shine the light on the semi-invisible chest to make it solidify.
Then face southeast and you will see a low platform. It has a harp symbol on it, but it might be hard to see. Shine light onto it and switch to Link. Get the 50 rupees from the chest that Medli solidified, then jump onto the platform where Medli is shining the light, and reflect the light onto the pieces of wall with the symbols on them, to make them crumble. Slide the now-revealed mirror into place. Go west through the archway in the wall, where there is another mirror. Slide it into place, then go to the southwest part of the room and slide the mirror there into place.
Then switch to Medli, go to the northwest part of the room, fly onto the platform that you just lit, then face east and shine light on the statue, face south and make the semi-invisible chest turn real, and face southwest and shine light on the wall symbol. Then turn southeast to face the little platform with the harp on it, and shine the light on it. As Link, get the joy pendant from the chest, then jump onto the platform where Medli is shining the light, and use Medli's light on the wall symbols behind her to make the wall crumble. Go to the mirror that you just revealed and slide it into place, then go toward the treasure chest that you opened, and go to the mirror in the archway nearby, and slide it into place.
Before you continue, make sure you have shone light on all the things listed in the previous paragraph. You won't be able to shine light on things after this next step. If you're ready, switch to Medli and fly northeast to land on one of the platforms near the mask on the north wall. Shine the light into its eye so that half of its face lights up. While Medli is still shining the light into the mask's eye, switch to Link, climb up onto the other platform, and shine the light into the other eye. Take Medli through the door.
Nintendo Gallery Note: Put Medli down and stay still. This is the best opportunity to get a picture of a Darknut with a shield. If you go too far into the room, blue bubbles will come to life and make it difficult for you to take the picture. Equip your camera, then slowly go into the room until the Darknut starts moving, then take the picture when it's close enough to fill the frame.
Put Medli down if you haven't already. Try to defeat the two blue bubbles in this room before fighting the Darknut. You need to use parry attacks (press A when it lights up) to cut away pieces of the Darknut's armor, then attack it, using your Boomerang to stun it if you have removed its helmet. When all the monsters are gone, open the chest to get the Big Key, then take Medli and go back to the last room.
Reach the Boss Door
Go to the right where there was a piece of wall with a single symbol on it. If Medli didn't crumble it, it is too late now. Take Medli through the door.
Drop Medli. There is a stalfos in each coffin. Shine the light on only one of the coffins, defeat the stalfos, then go back, pull the block out of the wall and climb it, and open another one. When they are all gone, open the chest to get treasure chart #12. Take Medli through the door.
As Medli, fly up onto the ledge along the south wall. As Link, climb up using the ladder on the left and join her there. Pick her up and go through the door.
Go up to the end of the stairs, put Medli down, climb the vines to the stairs above, then switch to Medli and fly to Link. As Link, pick up Medli, walk up the stairs to the ledge across from the boss door, and with her, jump and glide to the boss door. Use the jars to replenish health and items, and go inside. Medli stays behind.
Jalhalla
Nintendo Gallery Note: It's best to take a picture of Jalhalla now, although you will get a second chance before beating the game. Since Jalhalla moves slowly, it's easy to get his picture. Just get his head and as much of his body into the frame as you can.
If Jalhalla breathes in a bunch of air, roll away from him. If he blows air out, roll toward the center of the room. If he blows purple flames, roll to the side. Stay away from him if he turns blue, because if he lands on you, he will possess you temporarily.
It's not necessary to knock the lantern out of his hand. Just get into one of the beams of light, but keep in mind that the lights appear and disappear at random sometimes. Shine the light on Jalhalla. When he is solid, pick him up and throw him at a spiky column, not at the regular wall. He will break up into small poes. Defeat as many as you can with your sword.
Jalhalla will reappear after a while. Just repeat the above process until you have defeated him.
Afterward, pick up the Heart Container, then step into the glowing light in the middle of the room. There will be a cutscene.
If you didn't get a picture of Medli to make a figurine, you will have to come back to the boss room of the Earth Temple to take her picture.
When you're ready to move on, warp to the Forest Haven, and sail one square west of it, to reach Ice Ring Isle.