The Fused Shadow is a collection of four pieces of dark power that, combined, create what looks similar to a helmet from Twilight Princess. This object is one of the most powerful things that exists in Hyrule. Link is told by Faron that these items are the only things that would make Link more powerful than the King of Shadows, Zant.
The Fused Shadow was originally the shadow magic of a group of Interlopers, who tried to gain access to the Sacred Realm and take the Triforce. When they failed, their magic was sealed into the Fused Shadow by the Light Spirits, and broken into four fragments.
When the Interlopers were banished to the Twilight Realm after their failure, three of the fragments were left behind in Hyrule, and placed in dungeons for safe keeping. The fourth was apparently kept by the Interlopers and their descendants, who became the Twili.
When Zant - drunk with power granted by Ganondorf - cursed Midna into an imp form, he also stopped her from accessing the power that was hers as the Twilight Princess. Cast out and desperate, she summoned the last piece of Fused Shadow. Wearing this as a helmet, she followed Zant to the Light World and began to plan to recover the rest, intending to use it against Zant.
By the time Midna arrived in the Light World, Hyrule had been conquered by Zant and cloaked in Twilight. After talking to Princess Zelda, the deposed ruler, she went looking for the hero. She discovered Link, trapped in the form of a wolf. Remembering the Twili's legend that the hero would appear in the form of a "divine beast", she recruited him in her quest. She would go on to use the Fused Shadow's power to help him save the Light Spirits. Each time, this returned him to human form, and dispelled the Twilight in the area.
Her price was to help her to recover the other three pieces of Fused Shadow from the Forest Temple, Goron Mines and Lakebed Temple. Surprisingly, the Light Spirits who had sealed it long before agreed, encouraging Link to recover it to match Zant's power.
In each dungeon, the Fused Shadow had bonded with a creature, turning them into the Twilit monsters Diababa, Fyrus and Morpheel. Only by defeating them and driving out the dark power did Link and Midna recover the Fused Shadow fragments.
After the final piece of Fused Shadow was recovered from the Lakebed Temple, Zant appeared in Lanayru Spring before Midna and Link could use the complete Fused Shadow against him. Taking the three pieces they had found in the Light World, he mortally wounded Midna using Lanayru's light and retreated to the Twilight Realm. Midna was saved only by a personal sacrifice on Zelda's part, after which Hyrule Castle was sealed by a mysterious barrier.
Midna and Link then travelled through Hyrule to rebuild the Mirror of Twilight, aiming to travel to the Twilight Realm's Palace and fight Zant directly. After his defeat, Midna took the full Fused Shadow back and, angered by his taunting, used its power to pop him like a balloon.
Shocked by the power she could now wield, she and Link travelled to Hyrule Castle. There, Midna used the Fused Shadow to transform into a giant monster form and broke the barrier surrounding it, aiming to save Zelda in return for her help.
When they faced Ganondorf, he used Zelda's body against them in his attacks. This lasted until Link stunned him enough for Midna to use the Fused Shadow's power to purge him, after which Zelda's spirit returned to her own body. With Ganondorf recovering, Midna warped Link and Zelda to Hyrule Field, and aimed the entirety of the Fused Shadow's power against the self-proclaimed "King of Light and Shadow."
Triumphant, Ganondorf celebrated his victory, crumbling the helmeted part of the Fused Shadow in front of Zelda and Link. After his death, and Midna's restoration to her true self, the crumbled Shadow was seen still on the field where he dropped it.
- ↑ "In our world, we've long believed that the Hero would appear as a divine beast." — Midna, Twilight Princess.
- ↑ "We sealed away the great magic those individuals had mastered." — Lanayru, Twilight Princess.
- ↑ "You know this magic..." — Lanayru, Twilight Princess.
- ↑ "It is the dark power you seek... the Fused Shadow." — Lanayru, Twilight Princess.
- ↑ "But this world weeps beneath a mantle of shadows, and so there is no choice... You must match the power of the king of shadows." — Faron, Twilight Princess.
- ↑ "I... I used just a fraction of the power that's in me now..." — Midna, Twilight Princess.
- ↑ "I did THAT using only a fraction of my ancestors' magic?!" — Midna, Twilight Princess.