Talisman

The Talisman is an object created by the Guardian Knights, for the purpose of seeking out a being worthy enough to be deemed a Knight and aid in the battle against Quintessa. It has some degree of sentience, as it is able to alter its shape and even become mobile if that is necessary to fulfill its purpose.

According to the prophecy, the Talisman appearing is the first sign of the apocalypse, signalling the end of times. Some 'Bots would consider it wise to stay as far away from it as possible.

History
Long ago, the Talisman had arrived on Earth, taking the form of a Sword that would become lodged in a stone. During the Medieval Times, the Talisman would come into the possession of the Human who would become King Arthur, and come to be known as Excalibur. After Arthur's death, the Knights took possession of the object and kept it with them for the next 20,000 years.