Realm Crystal

The Realm Crystal is an ancient gem-like artifact created by the First Spinjitzu Master in the years following Ninjago's creation. The Crystal is capable of opening a portal to most of the Sixteen Realms (now fourteen after the destruction of the Cursed Realm and Djinjago), though it is uncapable of reaching the Departed Realm. Once kept in its creator's hidden tomb, at the bottom of the Endless Ocean, the Realm Crystal was sheltered from anyone hoping to travel to other realms at their disposal. When the Ninja found the Tomb and claimed the Crystal, they were confronted by Morro, who took the artifact and used it to free The Preeminent. After the Cursed Realm was destroyed, Morro gave the Crystal to his former master, Wu, who had it hidden away in Hiroshi's Labyrinth.

Some time after, the Realm Crystal was stolen by Nadakhan, who used it to free his crew from foreign realms. When the Ninja boarded Misfortune's Keep to find the lantern that would lead them to an island, Flintlocke shot his pistol at Cole, but the bullet passed through his ghostly form - shattering the Realm Crystal to pieces. Despite this, the artifact was eventually restored when Jay made his last wish.

Pre-Season 5
At some point in Ninjago's ancient past, the First Spinjitzu Master created the Realm Crystal and had it kept away in his Tomb so no one could have the power to cross between realms at will. After being freed from the Cursed Realm following Garmadon's banishment, Morro sought to find the Tomb of the First Spinjitzu Master to claim the Realm Crystal and unleash the Cursed Realm's prisoners.

Throughout the season, the Ninja pursued Morro, who had possessed Lloyd, across Ninjago in a desperate quest to make it to the Tomb before him.

Grave Danger
Through the use of R.E.X., the Ninja arrived at the Tomb first and claimed the Realm Crystal. However, Morro arrived shortly afterwards, threatening to harm Lloyd if they didn't give him the artifact. Kai threw Morro the Crystal, but using his element heated up the artifact - prompting Morro to drop it, and Lloyd, into the river below. While the Ninja managed to save Lloyd, the Crystal moved downriver until falling down a waterfall - yet Morro flew down and obtained the artifact before departing with it.

Curse World - Part I
Now in possession of the Realm Crystal, Morro went to Stiix and using the artifact released his closest allies, Wrayth, Soul Archer, Bansha and Ghoultar, before conjuring all the prisoners of the Cursed Realm. The ghosts occupied Stiix, taking over the city while the Ninja tried sneaking into it in an attempt to find and destroy the Realm Crystal.

After Nya, who is wearing Lloyd's suit, is captured by Morro and reveals herself, she incapacitates many of his allies using her element while Lloyd makes his way into Ronin's pawn shop - where the Realm Crystal is being held. With help from Ronin himself, Lloyd makes it inside and tries destroying the artifact, but is stopped by Morro, who reminds Lloyd of his father and that destroying the Crystal will prevent the two from seeing each other again. This distracts Lloyd long enough to be pulled into the Cursed Realm by the tentacles of The Preeminent, which emerges from the portal into Stiix.

Curse World - Part II
The Preeminent and the ghosts wreak havoc on the city, while Lloyd and Morro fight over the Realm Crystal and use the artifact to travel between multiple realms, including Cloud Kingdom and the Dark Realm, before Morro claims the artifact and escapes back into Ninjago - leaving Lloyd trapped in another dimension.

As The Preeminent is about to destroy the steamboat which carries all the city's citizens, Nya summons her water element and uses it to drown the colossal beast, killing it and dissolving all the Cursed Realm's prisoners. Morro tries escaping but is caught by one of the creature's tentacles and pulled towards the ocean. Wu tries to help Morro, and pleads for him to take his hand so he can do so, but Morro accepts his fate and hands the artifact to Wu before being dissolved by the sea.

Using the Realm Crystal, Wu brings Lloyd back into Ninjago.

Pre-Season 6
At some point, Sensei Wu gave the artifact to Cyrus Borg, who had it hidden away in a stronghold in Hiroshi's Labyrinth.

Infamous
After being freed from the Teapot of Tyrahn by Clouse, Nadakhan yearned to free his crew from the realms they were marooned across. He discovered that the artifact is hidden away in Hiroshi's Labyrinth, and set off to claim it.

Public Enemy Number One
Nadakhan arrived at the stronghold that kept the Realm Crystal, but was faced with multiple obstacles, including Security Droids. Despite the high-quality security system in the vault, Nadakhan eventually succeeds in retrieving the Realm Crystal.

Enkrypted
Nadakhan uses the Realm Crystal to gather his crew of Sky Pirates, and they set off to renew Misfortune's Keep.

Misfortune Rising
The Realm Crystal was kept on the bridge of Misfortune's Keep. However when Flintlocke tried to shoot Cole, his bullet went right through the Earth Ninja's ghostly form, instead hitting the Realm Crystal and shattering it apart. Incidentally, the last means of travelling to other realms was destroyed.

The Way Back
Jay's last wish caused the events that had transpired since Nadakhan's return to have never happened, thereby keeping the Realm Crystal intact and secure within the stronghold in Hiroshi's Labyrinth.

Realms

 * Chima
 * Cloud Kingdom
 * Cursed Realm (formerly)
 * Dark Realm
 * Ninjago
 * Djinjago (formerly)
 * Underworld
 * 8 other unknown realms

Appearances
{{Scroll|
 * 70736 Attack of the Morro Dragon
 * 70738 Final Flight of Destiny's Bounty

Season 5: Possession

 * 50. "Kingdom Come" (flashback)
 * 52. "​Grave Danger"
 * 53. "Curse World - Part I"
 * 54. "Curse World - Part II"

Season 6: Skybound
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 * 55. "Infamous"
 * 56. "Public Enemy Number One"
 * 57. "Enkrypted"
 * 58. "Misfortune Rising"