It’s a little tricky to get this skyshard. First, start at Trolhetta Wayshrine. Follow the road going northeast and at the first crossroads turn left. At the second crossroads turn left again. During this journey, at the point where road turns north for the second time, you will see Veldrana. She will give you the A Walk Above the Clouds quest which starts the Forelhost objective. This quest will help you on your way to get the skyshard. At the end of the road, climb up the stairs. In this area there is a hidden effect which rapidly reduces your health if you are in the open. The only way to prevent this is by standing near a source of fire. The area is dotted with torches dug into the ground, so what you have to do is run from one to another tourch and regenerate HP you lost while running between them. The quest you picked up will let you ignite a campfire at some places, too. As you advance through this quest, it will eventually lead you in front of stone doors. You have to solve a mini-puzzle to open the door (Snake in the middle, Eagle on the right, Whale on the left). After that, you have to pass through a dungeon to reach the exit. Once you exit the dungeon, you still have to be near a source of fire to prevent HP loss. Once again, quest will let you ignite campfires around. There is one torch on the left, and further ahead (to the south) you can see a stone gate with two more torches in front of it. The skyshard is lying on the ground next to them.
Veldrana starts the Forelhost Objective.
The area after you climb up the stairs.
You can ignite a campfire at some quest locations.
Stone doors and three nods used in the puzzle.
Area in front of the dungeon exit. You can see campfires around the quest objective.