Fyrus is the giant looking molten rock monster. To defeat him you must run to the opposite sid eof the room. Then take out your hero's bow and shoot him where he is glowing on the head. Now he is screaming in pain, so run up to where the chains are on his feet and pull the chains (while you have your iron boots on). He will fall over, so then you run up to his head and hit the glowing part with your sword. Repeat this until he is back to a normal goron. (note) if Fyrus ever uses the wave of fire go behind a supporter near the wall.