After you defeat the boss, go through the door and make your way to the right. Ahead of you will be a statue and as you approach, 5 shadow beings will appear. Kill them and then ride the rail to the top of the statue. Once you arrive at the top, a scene will play explaining the mirror of twilight. Now that you know the location of the mirror pieces, make your way to Zora’s Domain and hop off the waterfall at the cave entrance. When you land below, go through the cave to the left to enter the Snowpeak. As soon as you enter, transform to human form and talk to the person standing in front you. She will introduce herself as Ashei and give you a sketch. Open a warp to Kakariko Village and go to the graveyard where you received the armor earlier. Crawl through the opening in human form to find Ralis. Talk to him and then show him the sketch and he will give you his coral earring. He will tell you that you will need a reekfish and that they can be found in Zora’s Domain, at the base of the waterwall, near the mother-child rocks. Warp back to Zora’s Domain and drop off the waterfall and go to the shore opposite the Snowpeak entrance. Fish there and snag a reekfish and then turn into a wolf to sniff it and get the scent.
Continue to follow the trail across the ice floes and up the slopes. When it comes to a cliff face, go right and around up a ramp. Continue to another dead end and dash into the wall to drop the snow to reveal another slope. Keep following the trail to another dead end and dig to enter a tunnel. Follow the tunnel up the ladder, up the ledges, and up the vines to a door. Exit outside and continue following the trail to find 3 shadow beings. Defeat them and then transform to human and find the yeti on the cliff. Talk to him and he will tell you to follow him. Roll into the tree to drop a piece of ice and then slide down the hill to the ruins.