Fierce Deity Mask

The Fierce Deity's Mask is a mask in.

Location and Uses
The Fierce Deity's Mask is one of four Transformation Masks, the other three being the Deku Mask, the Goron Mask, and the Zora Mask. When worn, it transforms Link into the Fierce Deity. In this state, Link has an adult size and voice, and attacks with a double-handed, helix-edged sword which can release Sword Beams. Link has significantly greater strength and range while in this form. When obtained, it is suggested to be as dangerous as Majora's Mask.

Link can obtain the Fierce Deity's Mask by trading the twenty non-transformation masks to the four children inside the Moon. Since the Deku Mask, Goron Mask, and the Zora Mask cannot be traded, Link must have in his possession all of the other masks before being able to receive the Fierce Deity Mask. Once this has been done, the young hero obtains the mask from the child wearing Majora's Mask. He gives him the mask so that the two of them can "play" together. It is said to possess the merits of all masks, as well as the memories of all the people of Termina.

The Fierce Deity's Mask can only be used during boss battles, and, in, Fishing Holes. However, its combat capabilities are disabled inside Fishing Holes, and the Fishing Hole Men will forbid Link from leaving while wearing it.

Hyrule Warriors
In, the Fierce Deity's Mask appears as a type of Badge in the Bazaar that increases the amount of Special Attack Meters for each character, up to three bars.

In the Majora's Mask DLC Pack, Young Link's Mask weapon type is modeled after the Fierce Deity Mask. While Young Link primarily uses the Kokiri Sword in battle, he can temporarily transform into the Fierce Deity as part of Focus Spirit with the Mask. While in Focus Spirit, Young Link's sword transforms into the Fierce Deity's sword, and his attack power, speed and range is heightened for the duration of the Focus Spirit. As Young Link is able to play the to empty his Special Attack Meter and fill his Magic Meter, it is possible for Young Link to stay in his Focus Spirit for lengthy periods of time.

The Mask weapon type has two additional weapon tiers - the Furious Deity Mask, which has a purple aura, and the Vengeful Deity Mask, which has a red aura. These different variations causes Young Link's sword to transform into other swords while in Focus Spirit. The Mask weapon is of the Darkness element.

Trivia

 * Despite not being required to complete the game, Link obtaining the Fierce Deity's Mask is stated to be canon in.
 * In the Japanese text of the game, the child wearing Majora's Mask specifically states that he wants to play tag with Link. This is a play on words as the Japanese text states that the Fierce Deity Mask is a mask an (a type of Japanese ogre) wears, and the Japanese name for tag is "pretending to be an oni."
 * Early in development, an Adult Link Mask was meant to appear in the game, but was later replaced by the Fierce Deity's Mask. This may be due to the fact that Link can now use items that only Adult Link could in, rendering the mask useless. In Hyrule Historia, the Majora's Mask section contains concept art of Adult Link, confirming that Adult Link was meant to appear sometime during development.
 * Inside the game's code, a textured model of a Link mask can be found. It is possible that it was used to turn Link back into his Hylian form when wearing other transformation masks, as concept art in Hyrule Historia shows Deku Link wearing a similar mask.
 * The purple-ish aura which appears when Link is wearing/removing the mask is similar to what appears when Link(s) wear the Fierce Deity Armor outfit in Tri Force Heroes.