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.

The Fierce Deity's Mask can only be used during boss battles.

Hyrule Warriors
In, the Fierce Deity's Mask appears as a type of Badge in the Bazaar that increases the amount of Special Attack Meter for each character up to 3 bars.

In the Majora's Mask DLC Pack, it also appears as part of Young Link's moveset, where he can temporarily transform into the Fierce Deity. It is actually listed as his primary weapon, the others being the Furious Deity Mask and the Vengeful Deity Mask. A unique trait is that the Fierce Deity is Young Link's Focus Spirit and due to being able to spend his Special Meter to fill his Magic Meter, he can keep up Focus Spirit for lengthy periods of time.

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.