When Harry is trapped in the cage with the button, You cannot use him.Later, you will face two Hinkypinks.Defeat them and use Glacius to climb up on the mirror. Turn it , and use Glacius again but use Ron to climb up the frozen water near the orb thing and shine Lumos. Water will come out and use Glacius on it to make it into a ice block. Push it near the eye,but have someone block it in the middle. Shine Lumos on the orb on the ice block and it will shine into the eye.