Planetary Celestial Gate Keys (HoloArc)

The Planetary Celestial Gate Keys  (惑星星辰関基幹  Wakusei Seishin Seki Kikan ), more commonly known as the Behemoth Keys, are a set of eleven elusive keys which allows the wielder of them to summon forth one of these eleven Behemoths, Celestial Spirits of such power that they are said to be able to rival the might of gods.

Description
As previously stated, these mystical keys are utilized to summon extremely powerful Celestial Spirits. Unlike the Spirits summoned from the Zodiac Keys which represents a set of stars which forms into a constellation, the Behemoths summoned from the Planetary gate keys, each represents an important heavenly body in the solar system. The Behemoths are creatures of great will, making them very hard to control. In fact, if one wants the best out of these spirits, one should simply realize that one can not control them and that it is more about a connecting partnership rather than a situation of master and servant. The Behemoths will do as they please and will only follow those whom they deem worthy of following. Even then, they may rather prefer to do as they see fit.

Unlike the Zodiac Keys, which possesses a set amount of power, the Planetary keys deal more with various levels of power. A summoned behemoth's strength is fully dependent on the bond  which the spirit holds with its key's wielder. A poor relationship will not only lead to a disobedient spirit, but also to a very weak spirit. Each mage can only wield a single key as carrying more than one will carry with it the spirits scorn, making it impossible to utilize them at their absolute power.