The Mystery of the Stones is a puzzle that players will need to solve as part of the Octave of the Maushiro quest. Ruu will request that players help him solve some mysteries around the island, and players will need to use the new Peculiar Pinion item to help him out.
Players will need to follow the waypoint from the ceremonial area to the Wakukau Shaol. This is a short distance, and all they really need to do is drop down to the beach. There, they will see a ghost speaking to some stones after they use the Peculiar Pinion to activate one of the Electro bird statues near the waypoint.
The ghost will be examing some statues, and beside them is another bird statue. Activate it with the Peculiar Pinion and an Electro Seelie will form. Get close to it to activate it, then follow it around the area. It will travel near other statues and enemies, but just keep following it until it finally comes to rest and forms a small totem on the ground near another bird statue. Activate this statue with the Pinion to see some symbols on the wall, shown in the image below.
These symbols match the ones from the stones at the start of the area, so head back there and activate them in the correct order. You can see the exact order that players need to activate the stones below. To do this, hit them with an electro ability or attack.
Once that is complete, players can move on to the next part of the quest at Oina Beach, where they will need to solve yet another stone puzzle.