Guide:
Southeast Deshaan, southwest of Silent Mire Wayshrine, next to the Darkshade Caverns group dungeon.
Start at the Silent Mire Wayshrine and follow the road going west. At the crossroads turn south and at the end of that road you will come to the Darkshade Caverns dungeon. As you face the entrance go right and around, and you will see the skyshard on a small wooden platform, next to a wooden barrel and a wooden crate.
