Magic Cape
This mystical cape was found by Link in A Link to the Past under one of the Graves. Upon donning it, he found out that he would turn invisible and transparent, being able to pass through enemies and barriers at will. This came at a high price though, as the cape demanded a high amount of magic energy to sustain. The only way you can get into the cave is by performing a dash attack into the grave surrounded by dark colored rocks (the ones which can only be lifted using the Titan's Mitt) in the Graveyard.
The Magic Cape was necessary to gain access to one Piece of Heart by walking through a bumper on Death Mountain.