Kamidogu

The Kamidogu (from Japanese kamidōgu 神道具 literally "god tool" or "divine equipment"), now in the ownership of Shujinko, are mystic relics crafted by the Elder Gods which are said to contain the essence of the realms. When used in sorcery, they are said to have incredible power. Wielded by the wrong hands, the Kamidogu could endanger existence itself.

The Kamidogu embody the essence for each of their respective realms. Of the six Kamidogu that Shujinko collected in his quest during the events of Mortal Kombat: Deception, there was one pertaining to each realm: Earthrealm, Netherrealm, Chaosrealm, Outworld, Orderrealm, and Edenia.

Instilled with the essence of its realm, the appearance of a Kamidogu reflected the nature of its respective realm. The Kamidogu of the Netherrealm has an appearance that is visibly sinister. The Kamidogu of Edenia likewise, has a more serene look to it. When Shujinko was in possession of them, he was able to travel freely between the portals of the realms, by way of accessing the Nexus. However, it is revealed that there was one more Kamidogu that is connected to and surpasses all the other Kamidogus because it embodies the essence of not just one realm, but all of the universe. That final Kamidogu turned out to be the Sacred Amulet which is the Amulet of Shinnok.

The Kamidogu and Shujinko's Quest
The Kamidogu were introduced in Mortal Kombat: Deception and were the foundation of the story. More precisely, when playing Mortal Kombat: Deception's Konquest Mode, the player assumed the role of Shujinko in his quest for the Kamidogu.

Decades ago, Shujinko, was approached by an ethereal spirit entity that called itself Damashi. Damashi claimed to be the agent of the Elder Gods who was tasked with finding a mortal who had the courage and potential strength to undertake a quest for the Elder Gods. Shujinko, then only a child, eagerly accepted and Damashi charged him with gathering the six Kamidogu of Earthrealm, Netherrealm, Chaosrealm, Outworld, Orderrealm, and Edenia. To aid Shujinko in the quest, Damashi mystically instilled in Shujinko an enhanced ability to observe and then wield the Kombat abilities of warriors that he came across.

However, in reality, Damashi was not an agent of the Elder Gods, and the power granted to Shujinko was merely his own. Ages ago, the Dragon King, Onaga, was slain by Shao Kahn. But, even from the void, his essence could manifest within the realms. Damashi was actually Onaga's essence, extending into the realms. Thus disguised, "Damashi" was able to manipulate Shujinko into undertaking a quest to collect the Kamidogu. He even told Shujinko that he had not collected all of the Kamidogu because there was the last one left, the Sacred Amulet (the stolen Amulet of Shinnok).

Onaga, having acquired the Kamidogu, traveled to Outworld to re-assume his throne as the original ruler of the realm. From there, he intended to use the Kamidogu to attain ultimate power by re-making the realms in his image.

Shujinko, now fully understanding this threat to the realms, born from deception, resolved to stop Onaga. Though the heart of the quest was proven to be farce, Shujinko, having faced and triumphed over continuous dangers, had become one of the most powerful warriors in the realms. He journeyed to Outworld where he was able to gather a number of powerful warriors to one location. Then, using the mystic ability Onaga conveyed him with years earlier, Shujinko reached out for the warriors' essence, thus their combined powers supplemented his own.

Infused with such great power, Shujinko was ready to confront the Dragon King in Mortal Kombat. Shujinko proved to be more than a match for Onaga, who he was battling, but not before destroying the six Kamidogu and weakening Onaga, thus Shujinko defeated The Dragon King, ending the danger to the realms completing Shujinko's quest...for the moment. Shujinko among all the warriors feared that a victory against the Dragon King (later leading to the predicting events of Armageddon) was short lived.

The Kamidogu in the new Timeline
After the events of the past were altered by Raiden to prevent Armageddon, the Kamidogu once more play a pivotal role in the new timeline, with significant changes.

Reintroduced in the Mortal Kombat X (Comic Series) as daggers, the Kamidogu are now used to invoke powerful Blood Magick, by offering the daggers blood, either the wielder's own or someone else's, which can increase the powers of the wielder. However, there is a high cost for using the Kamidogu in such a way. One of the penalties is the draining of the user's strength by a large margin, leaving them severely weakened. Another penalty is that those cut by the blades become susceptible to possession by a powerful demon, and the only known way to be freed from the possession is to kill the victim. However, Raiden was able to purge his blood of the demon's influence during his own possession and return himself to sanity, and Sub-Zero was freed from the demon's control when the Blood Magik in his blood was used up.

One such victim of the possession was the Shirai Ryu Fox, who under the demon's influence slaughtered the clan, before he was killed by Takeda. Another was Sub-Zero, who's power was so enhanced by Blood Magik he was able to freeze an entire city and most of its population solid.

Four of the Kamidogu have been reintroduced so far: Three are currently in the hands of the thunder god, Raiden, while one is in possession of Kotal Kahn.

It is later revealed that each of the Kamidogu have tasted the blood of the One Being and its essence dwells within them, which is the source of their power. Raiden and the Elder Gods used the Kamidogu to seal Shinnok's amulet in a dark dimension, binding the seal in Raiden's blood. The corrupter of the Kamidogu, the cleric of chaos, Havik, seeks to claim them to obtain Shinnok's amulet.

Trivia

 * In the Mortal Kombat X (Comic Series), seven Kamidogu are depicted instead of six.