This part will take you through your second visit to the Sacred Grove.
Getting to the Sacred Grove
Our next part of the quest to find the Mirror Shards is to search for the one that's hidden in "a sacred grove", which we can easily figure out that it's talking about the one in North Faron Woods where we got the Master Sword. Before we head there, let's warp over to Kakariko Village and go into the graveyard to meet the glowing golden wolf waiting there. Again we will be taken to the white misty place where the Hero's Shade will teach us a new hidden skill after we've shown that we mastered the Mortal Draw. This new hidden skill is the Jump Strike, where we target one of our enemies and then press and hold down the A button for the right time to unleash the attack on multiple targets. As usual you'll have many tries to do this correctly.
Now warp over to North Faron Woods and change into Hylian form so you can go to the ledge that you used to enter the Sacred Grove. Rusl will meet you there and tell you about an ancient temple deep in the woods that the ancestors of the Hylians have created, that guards a sacred power which could go a long way toward saving Hyrule if somebody were to obtain it. He will ask us if we're willing to cross the gorge to find this power sleeping in the temple, and if we say yes, he will summon his "friend" to join us. It is a golden cucco, which Rusl will allow us to use to fly across the gorge.
So let's grab the cucco and leap off this ledge to the one right in front of us that's across the chasm, then leap over to the one on the right, then leap over to the one with the tunnel going through the tree. You'll notice that past the tunnel there's now only one bridge we must get to to reach the ledge on the right. Whip out your Gale Boomerang and turn the bridge so that you'll be able to fly over onto the bridge, then turn the bridge again to get onto the ledge. Up ahead are the two swinging stone pendulums with an island in between them we must jump onto. Safely time your leaps past the pendulums to reach the cave entrance that leads to the Sacred Grove.
Chasing after the Skull Kid again
When you enter the Sacred Grove, it will be dark, and the Skull Kid will appear in the first area you enter and blow his horn to summon his puppet horde to follow and attack you. Here we need to find him in three different places in the grove and attack him, but this time he will leave a clue that you're on the right trail by having his light shine at the end of a tunnel. The first place you'll find him is near a tree, where you can just go up to him and hit him with a sword strike. The second place will be on top of some rocks in the middle of a pool of water, and you can hit him with either an arrow or the Ball and Chain. The third place will be high on top of some trees, and you'll need to use the arrow to hit him. After the third hit, the Skull Kid will open up a door for you to follow him on a path that leads you to an arena where you must hit him three times while he's perched on one of the ledges while contending with his nasty little friends, the puppets. You'll be using your arrows for the most part to do that. When he is hit three times, the Skull Kid will laugh and then disappear, telling you that he will let you enter a secret place. Daylight will shine down on the grove as a door will open.
Going through the Door of Time
Go through the door and push a block on your left forward until it falls down into a small passageway you'll need to travel through. We'll get a good look at a statue that's guarding an ancient doorway that must be removed. Drop down into the passageway and head down through it to the courtyard in front of the door behind which is the pedestal that we got the Master Sword from. Go through the door into that area and insert the Master Sword into the pedestal, which will now remove the statue from the door. Link will pull the sword back out of the pedestal, and we can now head back up to that door. As we go through the courtyard again, though, we will get into an enclosed-space battle with five shadow beings, and making this battle more troublesome is that we have a swarm of winged creatures to contend with. Focus mostly on taking down the shadow beings so that you can create a Midna-warp spot to return to this place later on. Now head back up the passageway to the door that the statue once blocked and go through it. The door will mysteriously transport you through time into a temple that was fully constructed on the spot where the Sacred Grove is now. Go down the stairs and past the court with the two statues into the room with the pedestal and place the Master Sword into it. A glowing blue staircase will go up to one of the stained-glass windows in that room of the temple, and Link will see an Oocca with her hatchling go up the steps and through the window, indicating that it's an entrance to a hidden part of the temple. We might as well follow them up the stairs and enter.