The Phantom Helmet is a helm found in Breath of the Wild. It has a base defense of 8, and was released as a part of the first DLC expansion for the game: The Master Trials.
"Myths abound about armored phantoms that terrorized brave heroes. This helmet looks just like the ones they supposedly wore. If sold, this rare find can’t be replaced."
As part of the EX Treasure: Phantasma side quest, Link will find this piece of armor at the Coliseum Ruins. The buried treasure is located on the ground floor right along the wall at northwest portion of the ruins. Link can use Magnesis to easily spot the chest and pull it out of the ground. Be sure to check our Interactive Map for a more precise location.
After Link has obtained this item for the first time, he will be able to purchase it from Granté in Tarrey Town for 50 Rupees.
The Phantom Helmet is part of the Phantom Set, which also includes the Phantom Armor and Phantom Greaves. When individually equipped, they will give Link an Attack Up boost. None of the items in the set are enhanceable or dyeable.
The chest is along the northwest wall of the Coliseum Ruins. Use Magnesis to more easily spot its location.