Nightmare Key

Big Keys, also known as Boss Keys, and Nightmare Keys, are recurring items in.

Location and Uses
Boss Keys are one of the three standard dungeon items, the other two being the Compass and the Dungeon Map. They are generally harder to find than Small Keys and are used to open the big door leading to the boss' chamber.

In, Big Keys are also used to open the Treasure Chests containing the dungeon's item. Also, doors unlocked by the Big Key may not necessarily lead directly to the boss.

In, Nightmare Keys open access to the Dungeon's Nightmare.

In, the Big Key from the Goron Mines must be put together by obtaining the three Key Shards from the Goron Elders. In Snowpeak Ruins, the Big Key is replaced by the Bedroom Key, as said dungeon is actually the mansion residence of Yeto and Yeta.

In, Link must carry the Boss Key in his hands rather than inventory, making him unable to attack and vulnerable to attacks.

In, Link must carry the Boss Key in his hands rather than inventory, making him unable to attack and vulnerable to attacks. In some instances, Keys are electrified and Link must have Princess Zelda possess a Phantom in order to carry them for him.