Orichalcos Stone
The Orichalcos Stone is the crystal that powers "The Seal of Orichalcos" in the Waking the Dragons arc, named for the legendary material "Orichalcum" featured in one of Plato's dialogues which also contained the characters "Critias" and "Timaeus". They were created by The Great Leviathan.
Features
To wield a fragment of the stone, the owner must be deemed worthy by it. If so, they are able to hold the stone in their hand and be granted great power. If they're not, their souls are taken by the stone and fed to the Great Leviathan. The stones are maintained by the darkness within the owner's heart, just like the Seal of Orichalcos magic card. The darker the owner's heart, the more power he can access. But, if they overcome the darkness, the stone will shatter to pieces.
While under the influence of the Orichalcos, their minds are warped with psychological disruption which causes them to lose their personal self to the darkest abyss.
While playing the Seal of Orichalcos with or without, their dueling style and strategy become brutal and violent; that they can lose reason to use their own will to duel like Yami Yugi did when he duel against Rafael; he begins to disrespect his cards and sacrifice his own monsters using Catapult Turtle in order to win. Yugi also uses this strategy in order for Yami Yugi to counter this monster sacrifice which can free him from the Orichalcos influence which in fact corrupted him and the darkness that dwells in his heart.
The people who are chosen by the stone gain strength and mystical powers that rival the Millennium Items. They have the power to materialize Duel Monsters. When inside the seal, it even allows the owner to control an Egyptian God. When the stone is thrown to the ground, it summons one or more Orichalcos Soldiers. A wielder of a stone can also destroy the soldiers at will, like Valon did to spare Joey Wheeler. They also have the power to unlock and dispel the Seal of Orichalcos, but only from the outside, and at the risk of the owner's soul. Other abilities include casting illusions, teleportation, and showing mental visions.