Seal of Phobos

The Seal of Phobos is a rhombus-shaped magical jeweled item that allows the user to open portals.

History
It was stolen by two officers and the nanny Galgheita (also known as the math teacher Mrs. Rudolph) to take Elyon as a baby to Earth to protect her from her brother, Phobos who originally created his amulet.

It was hidden in the cavern behind the basement of the Portrait family's house and was discovered by the Guardians. The seal is absorbed by the Heart of Kandrakar to save the girls' lives.

It is used to open portals but it eventually becomes useless.

It was the symbol of the royal family of Meridian, so that Cedric and Elyon uses the symbol of the Seal of Phobos on their clothes, he also seems to have a conscience itself, and is capable of delivering powerful beams of dark energy, or a kind of black mud (true form of evil, according to Oracle).