Dominion Rod
The Dominion Rod is found in the Temple of Time, the sixth dungeon in Twilight Princess, and is used to bring certain statues to life. This allows Link to control them. If you walk in a certain direction, the statue will follow. Press the button with the Dominion Rod on it and the statue will perform an attack.
Once leaving the portal that links the Sacred Grove to the Temple of Time, the Dominion Rod will lose its power. After receiving a 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 will restore power to Link's Dominion Rod. He must then travel across Hyrule to various Owl Statues, and use the power of the Dominion Rod to move the statues. Under each one contains an ancient character, and Link will need to acquire each one to complete the book.
Once Link returns to Kakariko Village and gives the researcher 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 an enormous, yet damaged cannon. Link then gets Midna to warp the cannon to Lake Hylia. Here Link pays a rather whopping fee (300 Rupees) to a man named Fyer who fixes the cannon. It is here that Link finally begins his journey into the City in the Sky.
The Dominion Rod is the key item used to defeat the boss in the Temple of Time, Armogohma, the latest reincarnation of Gohma, a boss who appears in many previous Zelda games.