Merge:M'Kraan Crystal

In the, the M'Kraan Crystal (pronounced "EM-kron") is a gigantic crystalline artifact that lies at the nexus of all realities. The Crystal also serves as a housing for an endless city and an orb that contains a neutron galaxy. The Crystal plays a prominent role in several major storylines, including the Dark Phoenix Saga and the Age of Apocalypse. Stated in the Saga was that Phoenix Force was the guardian of the crystal that the legend tells of.

Abilities
As the Nexus of all Realities, the Crystal can allow travel between universes, but opening the Crystal could cause the mass of the neutron galaxy inside to suck in the entire universe and cause a chain-reaction across the multiverse, destroying all universes in existence. The city inside can only be reached once every million years: when specific galaxies are aligned, the M'Kraan Crystal will allow entry for a short period of time. It also houses the White Hot Room, the place in which Phoenix Force places all beings to heal them or return them to life.

History
The M'Kraan Crystal first appeared in Uncanny X-Men#107. Placed on an abandoned planet, known only as The World, the Crystal was considered sacred by the alien race known as the Shi'ar, a symbol of their faith. The mad Shi'ar emperor D'Ken wanted to use its legendary power for his own ends, and so D'Ken's sister Lilandra Neramani allied herself with the X-Men to stop her brother's mad quest, knowing that the Crystal was nicknamed "The End of All That Is". The Phoenix Force, still weakened and unexperienced in using the new host body of Jean Grey, flew to the crystal to try and stop D'Ken, but was sucked in, with everyone else. Inside they found a large endless city, at the center of which was the heart of the Crystal - a sphere which contained a Neutron Galaxy. The X-men, along with D'Ken, were rendered immobile by a ray coming out of the orb, which caused everyone to live out their greatest nightmares. Only Phoenix was unaffected. Using her empathic link she had with the crystal, Phoenix discovered an energy field in the form of a latticework, which acted as a living shield - for the Neutron Galaxy was deteriorating and due to it's intense gravity, would cause all of creation to be sucked into it. Phoenix used her powers to try and repair the latticework but found she wasn't strong enough, so she reached out telepathically to her fellow X-Men for aid, and with their combined power Phoenix was able to repair the Crystal and thus save the universe from ultimate destruction.

During the Age of Apocalypse, it was found out that a small shard of the M'Kraan Crystal contains the power of the full Crystal. Apocalypse was planning on using the Crystal to conquer other universes, but Bishop used the Crystal to travel back in time and restored reality. A small shard of the Crystal was responsible for moving X-Man and Holocaust from the Age of Apocalypse Earth to Earth 616, while Sugar Man and Dark Beast entered a larger version to make the same trip. Holocaust would have this shard embedded in him for a while, draining power from the Crystal until X-Man removed it.

As it is a singleton across all universes, the reality-hopping Exiles have recently figured out how to use the Crystal to visit selected realities; on the Age of Apocalypse Earth, Dark Beast discovered a means to travel through the Crystal to alternate Earths. The Exiles used it as a means to reach the Panoptichron, a place that exists outside of time and space.

Guardians
The M'Kraan Crystal is guarded by Jahf, a small android with tremendous strength and durability. Should Jahf be defeated, the gigantic robot Modt takes its place. Modt is said to be a thousand times stronger and more powerful than Jahf. Modt claimed that should he be defeated an even more powerful guardian would appear, and that an endless number of increasingly powerful guardians were waiting beyond him. So far nobody has been able to defeat Modt. These Guardians seem to exist in all different realities simultaneously, as Jahf in the Age of Apocalypse had knowledge of the events on Earth 616.

Should the Guardians be avoided, a second layer of defense exists: any person entering the M'Kraan crystal will live through his greatest fears.

The Phoenix Force generally protects the M'Kraan Crystal against abuse as well. The White Hot Room, home to all the avatars and hosts of the Phoenix Force, is located within the City inside the Crystal.