Crouch and follow behind him. He sometimes falls, then looks back. If he moves too far away, close the distance during the displayed countdown.

Enter the passage he uses and open the Heavy Gate with Yi Dao.

From the trap, continue straight and take the right-hand path near the dead end. Use Wind Sense (opens in a new tab) to reveal bloodstains among the fire traps. Carry the Statue beyond the fire mechanisms back to Yi Dao.

Place the Statue on one pressure slab and stand on the other. Proceed with Yi Dao; the following encounter gives you the Engraved Key.