Fused Shadows are parts of a weapon made by the Dark Interlopers in a plan to take the Triforce. When there plan was foiled they were sent into the Mirror of Twilight to rot forever. They started a race which eventually became what is now known as the Twili. The Fused Shadows after the Dark Interlopers were sent away were sealed away in dark Dungeons across Hyrule in the hopes that they wold never be formed together again. Midna after being cursed by Zant thinks that the Fused Shadows could be used along with the one piece she had to turn herself back to normal and take back the throne. Link and Midna go and find these Fused Shadows but after finding them ant takes them from her before she can use them. Later after the Mirror of Twilight is remade Link and Midna go to the Twilight Realm where they take back the Fused Shadows and Midna uses them to kill Zant. Later again Midna uses there full power to break into Hyrule Castle.