Sealing Crystal

Sealing Crystal is a magic item that can seal high level spells.

Description
In the New World, sealing crystals are legendary items imbued with great power. The legends and tales revolving around these items originate from the Slane Theocracy. The nation is said to possess one at its founding and that it's a treasure left behind six-hundred years ago by the Six Great Gods. This items was the basis of the Slane Theocracy’s doctrine until its current holder Nigun Grid Luin used it in a failed attempt to defeat Ainz Ooal Gown by summoning a high rank angel.

Appearance
Sealing crystals seem to come in a variety of shapes and hold a quality of brilliance depending on what types of magic they contain.

Abilities
Sealing crystals are incredibly powerful artifacts in the New World, as they are capable of containing rank seven or higher magic, an impossible feat for humans who are unable to contain or cast such magic. Thus, sealing crystals are considered extremely valuable to any nation that possesses one. The magic released by a sealing crystal can only be used once, so holders of these items would only use them as a last resort.

Afterwards, one must go to great expense and perform extensive rituals to recharge the spell within the crystal.

Trivia

 * Magic Casters highly prize these sealing crystals as they are a subject of much debate and study.
 * In the official manga, the Sealing Crystal was shattered into pieces when the summon it held was released from confinement.