The Seal of Phobos is a magical, rhombus-shaped, jewelled medal-like artrifact that allows the user to open portals, and it was originally created by the young, tyrannical wizard Prince Phobos.
It was stolen by 2 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 once possessed 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 W.I.T.C.H. 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, although the Seal 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).
- In the W.I.T.C.H. comic book series, the Seal of Phobos appears to have a very similar way to the Heart of Kandrakar, maybe by this format because it has been changed to a perfect lozenge in the TV series, to avoid the similarity between two objects.
- The similarity between the Heart of Kandrakar and the Seal of Phobos can be explained by the obsession of Phobos by heart, but this fact can not be entirely true, since the seal was a symbol of the royal family of Meridian.
- ◾In the comic book, Phobos releases a kind of pitch black mud that almost covers all the W.I.T.C.H. girls; this same "pitch" black occurred when Nerissa invades Kandrakar and shows that Oracle is the true form of evil.
- In the TV series W.I.T.C.H., Phobos appears to not be able to open portals, but he is the true creator of the Seal of Phobos, his own namesake amulet that opens doorways, which is odd, leaving the question of how he created this gem.
- In one of the gifts of the comic book, the tarot witch, there is a letter in which the Oracle holds a balance scale where they are in the Heart of Kandrakar and the Seal of Phobos.
- The Seal of Phobos is maybe the symbol of the royal family of Meridian, which is why the icon in Phobos' castle, and on the clothing of both Cedric and Elyon is the symbol of the seal.
- The Seal of Phobos looks like the Seal of Nerissa in "Arc 2".