Boss key?

Use your Clawshot to remove the armor from the two small enemies in the room, then defeat them with your sword. Next, you should go after the big, armored guy. Use the Back Roll to slice the flashing part on his back. Keep doing this until he goes psycho and blows himself up. Clawshot up to the higher platform, and set a small statue on each of the switches. Now use the Clawshot to grab one of the white suits of armor on the ground and place it on the final switch. This will open the door to the boss key.