Dominion Rod

The Dominion Rod, also known as the rod of the heavens, is an item first introduced in Twilight Princess, and is used to bring certain statues to life. This causes the statues to mimic its master's movements: if Link walks in a certain direction, the statue will move in that same direction. Pressing the button that the Dominion Rod is set to causes the statue to perform an attack.

Background Story
Back when the sky beings known as the Oocca still maintained contact with the Royal Family of Hyrule, the Oocca handed down a mysterious rod known as the Dominion Rod. This rod was only to be carried by one known as the messenger to the heavens, and it would be used by the messenger whenever the Royal Family needed to communicate with the Oocca. Along with the rod of the heavens, the sky beings left the Ancient Sky Book with the Sheikah, which was to be given specifically to the heavenly messenger.

Location
When the events of the game begin, the Dominion Rod is found in the eighth and highest floor of the sixth dungeon, the Temple of Time. However, the temple itself is destroyed in present time, so when Link visits the Sacred Grove while looking for a fragment of the Mirror of Twilight, he has to cross a gate that takes him to the past, in a time when the temple is still active. Link gains the item after defeating a Darknut.

Uses
There are four types of statues Link can move with the Dominion Rod. The first type are small statuettes in the Temple of Time that are mainly used to weigh down switches. The second type is a much larger statue that holds a hammer, which Link must guide through the Temple to its original position. This statue can attack enemies with its hammer. The third type of statues are gigantic statues found only in one room that Link must use to defeat Armogohma. The last type are Owl Statues: the only statues located outside the Temple of Time. They are primarily moved to obtain the missing Ancient Sky Book characters, or to create platforms for Link to jump on.

The Dominion Rod is the key item used to defeat the boss in the Temple of Time, Armogohma, the latest incarnation of Gohma.

Aftermath
Once Link leaves the portal that connects the Sacred Grove to the Temple of Time, the Dominion Rod loses its power. After receiving the Ancient Sky Book containing sky language and giving it to a man named Shad, who has recently discovered an owl statue different from other ones he has seen across Hyrule, he will read the text, only to fail to open the path that leads to the heavens. However, the ancient text he reads is a spell which restores power to the Dominion Rod. Link must then travel across Hyrule to various Owl Statues, and use the power of the rod of the heavens to move the statues. Under each one contains an ancient character, which Link needs to acquire to complete the book.

When Link returns to Kakariko Village and gives Shad the completed book, he changes the strange statue's composition, but fails to make it budge. Link uses the Dominion Rod to move the owl statue, and finds a small tunnel leading to a room containing the enormous, yet damaged Sky Cannon. Link then gets Midna to warp the cannon to Lake Hylia. Here Link pays a fee of 300 Rupees to a man named Fyer to get the cannon fixed. It is here that Link finally begins his journey into the City in the Sky.

Trivia

 * Along the walls of the Temple of Time, there are carvings depicting what looks to be the Seven Sages. One of the Sages is holding the Dominion Rod.
 * When Link wields the Dominion Rod, the ball of light that animates the statues is green. This could be the light's default color, but it's also possible that the color changes to reflect the person controlling the statue, in this case the green-clad hero. Theoretically, if another character were to use the Dominion Rod, the light might change color, but this is never observed and thus cannot be proven.
 * If Link exits the Temple before finishing, via Ooccoo Jr. or by foot, the Dominion Rod will be depleted and the item description will reflect Ooccoo's explanation, despite Link not knowing this yet.