Misko's Treasure of Awakening III
Tears of the Kingdom
"On Hyrule Ridge, in Ludfo's land, ruins sleep beneath the towering mushroom trees. Connect the southern column's midday shadow to the northern. At the shadow's center, the way to my treasure will open."
This starts by reading the tablet in the cave at the end of Misko's Treasure of Awakening II. Go to the Thundra Plateau and, as per the hint, open the Thundra Plateau Cave by extending a shadow from the southern column to the northern. This can be done by attaching four logs from felled nearby mushroom trees, standing on top of the southern tower and raising them, and waiting until after noon. Link will receive the Mask of Awakening upon opening the treasure chest, thereby completing the Hero of Awakening Set.
"To the one who found my treasure, you've done well to solve my riddle and make it to this place. Your cleverness and cunning have earned you both the treasure and my respect. -The Great Bandit Misko"