Mirror-Caliban
Mirror-Caliban is the name of a sub-realm located and hidden within the motherfucking Warp, that was subconsciously created by Lion El'Jonson after a 10,000 year snooze fest. Yeah...don't ask us how that happened, although there are multiple theories ranging from being the creation of the Emprah, to being the original home of the Watchers in the Dark. Whatever is the case, this sub-realm is now treated as the Lion's personal training course. Awesome.
Overview[edit]
Mirror-Caliban as its name implies, heavily resembles the Lion's old home. The sub-realm is an endless expanse of forests shrouded in mysterious mist. As his own personal realm, the Lion can enter it free of charge.
It is speculated by the Primarch to be a realm that is adjacent to the Warp, which was perhaps conjured from El'Jonson's youthful memories. We know that the Warp is heavily influenced by the minds of greater or collective entities, so it can be hinted that the Lion dreaming this place into existence may lay more on his Emprah lineage than anything else. As previously mentioned, the realm is truly endless, and is home to the Watchers in the Dark and the Great Beasts that the Primarch once hunted. The only other inhabitant in Mirror-Caliban, is an old wounded king who slowly bleeds from his injuries and is always stalked by hungering shadows. The king cannot speak and simply stares in space or directly at those he sees like a paraplegic couched potato. If this guy is giving massive Emprah-vibes, then yeah, because he is the Emprah.
According to a Watcher in the Dark, however, the king is capable of answering questions, should the right one be asked of him. He can either be found fishing on a boat in a river or sitting within a castle that is located nearby. Wherever he is, he is always stalked by the shadows, which the Watchers warned the Lion to not dip his toes in it.
One of the more mysterious structure in this realm, is the appearance of a domed building, which was treated like a Pandora's box, as a Watcher appeared and warned the Primarch against entering it, stating he was not yet strong enough to safely do so.
During the Lion's Arthurian arc, the Primarch learned how to freely enter Mirror-Caliban and use it to reach other worlds. By focusing on where he wants to go, El'Jonson causes the location to slowly appear within realm, until its forest finally fades away and the Primarch enters his destination. This ability is known as the Forestwalk, which also allows El'Jonson to take others with him upon these journeys. In a nutshell, the Lion can now teleport as he pleases. Yeah. If the Lion isn't already a scary motherfucker, he is now.
To the Lion's opponents, when the Lion activates his protagonist's abilities, an apparition of the forest suddenly appears from nowhere and then fades away after the Primarch walks out of it. Despite this ability, though, El'Jonson sometimes enters Mirror-Caliban after sensing something drawing his attention to the realm. Upon doing so, he is then teleported to another location, which the Lion discovers contains Fallen Angels. The Primarch does not know, however, if this feeling that leads him to his wayward sons is an instinct of his or if another force within Mirror-Caliban is pulling him towards the Fallen Angels.
The mysterious realm is also a 40k Legend of Zelda questline, as it houses the mysterious power sword Fealty and the Emperor's Shield of all things, until both were discovered by El'Jonson. The latter was contained in the domed building the Watcher had warned him against entering and upon doing so anyways, El'Jonson fought the only other unique inhabitant in the realm, which is a unique shape-shifting maybe-Daemon that could change into the forms of his brother Primarchs. This ability caused him to be overwhelmed by the creature, until El'Jonson found the Emperor's Shield within the building and used its powers to destroy the Daemon. Another theory could be that this boss fight was a construct of The Watchers and/or Daddy created to serve as training for The Lion, as well to protect some of the Mjolnir-tier weapons Big-E had stored there. Speaking of, the idea of using a realm within the warp to house valuables is interesting, and seems to be new as well. It brings to mind the pocket dimensions the Necrons use to teleport and occasionally store things, but that's certainly not the warp. Whether this is entirely new, actually has any precedent, or is just the author playing it a bit loose with the rules of the warp, it's still cool and has a lot of interesting possible implications.