Spear Key

The Spear Key (Japanese: やりのカギ Spear Key) is a special artifact in the. It is a powerful object capable of locating ancient Legendary artifacts. With the Spear Key having such effects, it was retrieved by Team Galactic, who used it in their various schemes.

In the anime
In Journey To The Unown!, Saturn and two Team Galactic Grunts headed inside the Solaceon Ruins. In an inner chamber, they placed the Splash Plate, Draco Plate, and Iron Plate into slots on the floor, which released the Spear Key in the form of a cube.

Later, in Enter Galactic!, Saturn and more Grunts arrived at the site of the meteorites in Veilstone City so that the power of the meteorites could activate the Spear Key.

In Double Team Turnover!, the Spear Key was used by Jupiter to locate the Lustrous Orb, which had been stolen by. At the end of the episode, the Spear Key, along with the Lustrous and Adamant Orbs, were seen attached to machines in Team Galactic's base.

In Steeling Peace of Mind! and Saving the World From Ruins!, the Spear Key was used by Mars at Iron Island to scan Mt. Coronet so as to find the exact location of the Spear Pillar.

In Gateway to Ruin!, the Spear Key was used by Saturn and Charon to find some ruins in Mt. Coronet. When it was found, the Spear Key did not react to it, indicating that those were the wrong ruins, and thus they retreated.

In Unlocking the Red Chain of Events!, Saturn used the key at some other ruins on Mt. Coronet. The Spear Key reacted, indicating they finally found the Spear Pillar. In Battle Finale of Legend!, Cyrus used the key to open these ruins, revealing a staircase leading to the Spear Pillar. After Team Galactic was defeated and and  returned to their dimensions, the Adamant and Lustrous Orbs were retrieved, but the Spear Key seemingly disappeared.

Trivia

 * A picture on the TV Tokyo Pokémon website shows the Spear Key in its activated form inside a portal, surrounded by the lake guardians, which foreshadowed the events of Battle Finale of Legend!.
 * Its name is a very obvious reference to the Spear Pillar, indicating that the two share a connection.
 * The three plates used to summon the Spear Key refer to Dialga and Palkia: the Splash Plate to Palkia's, the Iron Plate to Dialga's , and the Draco Plate to the that both Pokémon share.