Operencia: The Stolen Sun

After you defeat the Ancient Elemental boss, find the fake wall along the west side of the room. After entering this area, return to the boss room and you can now rotate the "dice" by pressing the buttons alongside them on the floor. Take note that you can rotate them both horizontally and vertically using buttons on each side of the dice.

For this achievement, simply rotate all 4 dice so they display a skull icon.