WARNING: The following article contains spoilers for Excalibur #12 by Tini Howard, Marcus To, Erick Arciniega, and VC's Ariana Maher, on sale now.

Created by Rob Liefeld, Fabian Nicieza and Mark Pacella in 1992's X-Force #10, the Externals are an ancient group of mutants with a rare mutation that grants them immortality and ties them together through a psychic link. This link allows them to know each other's location, summon each other across vast distances, and sense whenever one of their numbers has been killed or returned to life.

This brings up another fact about the ancient organization: death does not have a conventional hold on them. As part of their immortality, they have a powerful healing ability that can return them to life if they are struck down, in some cases dying and then returning years later, occasionally in a different form. Even though they are seemingly indestructible, there do exist more permanent ways to kill the Externals. Destroying the heart of an External is the only known way to permanently kill them, but even that has a negative outcome as the life force of the slain External channels into the surviving members of the group, making them even more powerful.

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The Externals are a secret Illuminati-like organization that specializes in manipulating events from the shadows, particularly those that affect the lives of mutants. Most of the members of the Externals have at some point been antagonists of the X-Men, the most prominent among them being Apocalypse. In fact, they are even credited with helping to create the dystopian world depicted in 1995's Age of Apocalypse crossover event. 

In Excalibur #12, Apocalypse has gathered his fellow Externals to speak to them about how the mutants of Krakoa have changed. Coming to the conclusion that they have evolved to the point where they stand as equals in power to the Externals, Apocalypse desires nothing more than to help them achieve their place of freedom by using what he believes the Externals to lack: A sense of community.

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Wishing to use the life energy of several Externals to open a Krakoan gate into Otherworld, Apocalypse had hopes that his peers would surrender willingly, but anticipated their refusal. With the aid of Rictor and the Externals Selene and Gideon, Apocalypse successfully killed the remaining members. Acknowledging what would happen if he permanently killed more than one External, Apocalypse had a plan in place to use this to his advantage.

Setting up the bones of his fallen colleagues in a ritual, Apocalypse intended to redirect their power into the creation of a portal from Krakoa to the Otherworld, thus circumventing the massive influx of power that would have come to him and doing a service for his people. With a little aid from Gambit, who tossed in one last External's life energy to make the ritual work, Apocalypse successfully opened a portal to Otherworld on the literal bones of his allies, expanding the reach of the mutants into the magical dimension. This is a boon to the X-Men's already massive power structure, and may prove indispensable in the upcoming X of Swords event.

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