The Amulet of Will is a powerful artifact once used by Lord Casterwill in summoning and alluded to in the journal of Eathon Lambert. Legend states that anyone attempting to control one of the three Legendary Titans, Araknos, Behemoth, or Tao, without the Amulet of Will will be cursed. The four gems of the Amulet of Will represent these three Legendary Titans as well as the Legendary Titan of Immortality, Overlos: blue for Tao, green for Behemoth, red for Araknos, and white for Overlos, who was sealed in the Amulet of Will.
History
Like the other Amulets, the Amulet of Will was forged in ancient history by Lord Casterwill in order to summon the Titans to do battle with the Nullifiers. The Amulet of Will was the original Amulet on Earth and was used to summon all other Titans from the Spirit World - Huntik. Due to the Legendary Titan of Immortality, Overlos, being sealed within this Amulet, Lord Casterwill was able to live for the 500 years' duration of the war.
Some time after this war ended, Casterwill cursed the Rings of the Legendary Titans, Araknos, Behemoth, and Tao, to prevent anyone from bonding with them without the Amulet of Will. After Casterwill died, the history of the Amulet of Will is ambiguous at best and remains a gradually unfolding mystery.
The last known Seeker to have come close to finding the Amulet of Will was Eathon Lambert, but he vanished before he could reach it. Eathon kept a detailed journal with clues leading to the Amulet of Will, but it was damaged after being found by Eathon's son, Lok Lambert, while being chased by the Organization's Suits. S1E01
After a long search through clues left about the Amulet of Will, it was discovered and acquired by Lok Lambert for Dante Vale's team in the Huntik Foundation. Using the Rings of Tao and Behemoth were acquired by Lok and Dante, respectively. However, thanks to a ploy by the Professor claiming to cure Dante's friend, Metz, from his curse, the Rings and the Amulet of Will fell into the possession of the Organization.
Using a ritual he had uncovered through vast amounts of the Organization's research, the Professor attempted to use these artifacts to summon the Legendary Titan of Immortality - Overlos. However, with some quick thinking from Lok, Overlos' power came under the control of the Foundation. Under Lok's command, Overlos and the three Legendary Titans, as well as their Rings, were sent back to the Spirit World.