The Cataclysm
The Cataclysm was an apocalyptic event that took place at The Spire in 2016. Though many of the details surrounding the Cataclysm remain unclear, what unfolded resulted in the destruction of most of the Lunar Children and the disappearance of the Spire from physical reality.
History
While the exact causes of the Cataclysm are unknown, there were a number of likely causal factors that lead up to it. Early in 2015, the players were contacted by Mason and provided him with the blueprints for the construction of a Data Bomb that were found in Doug's notes. During this time, Mason had been left by IsocelesAssassin and was slowly gaining the ability to manifest some form of a spiritual body from his electronic cage. After receiving these plans, Mason devised a way to use the electronic device he was trapped in as such a bomb, and began the long journey to the Spire on foot.
From inside the cult, Mat began communicating with Tenebris against the wishes of the other Elder Children. Despite being caught and reprimanded, Mat continued these communications and seemingly inspired worship of Tenebris among the lower ranking members of the cult. A rise in vocal support for Tenebris led Jinn and Thoth to discuss doing something about Mat. Jinn wanted to make use of the knowledge from Mat's communions, and convinced Thoth to secretly bug Mat's room and observe the communions instead of stopping them. She then spoke with Hunter and gave him the responsibility of keeping an eye on the other Lunar Children to watch out for any level of dissent that might jeopardize Undecim Nocte. During this conversation, she noted that the group of dissenters were congregating in the Spire's basement — the same location containing the black cube that was brought over from the Fishery.
On Undecim Nocte, 2015, the Lunar Children were unable to hold Tyler for long. Aside from the Harbingers' intervention, many things went awry; Hunter went against orders and delivered the Crescent Moon Necklace to Tyler; Doug, likely under the control of Tenebris, had left the Fishery in order to torment Tyler at the Spire; and both Mat, Hunter, and Doug disappeared after the ordeal finished.
The Cataclysm itself occurred on April 23, 2016. At 11:11 AM, Doug's account posted, "It is time for Her to feed" on the Lunar Children Forums. It is unknown what exactly occurred following this; however, it is known that whatever unfolded was unexpected and caused a great deal of panic in the spire, and that at some point, Patrem was "sucked into something", resulting in Vincent being freed from his control. As well, images posted by The Producer possibly imply that Mat was present in the basement on this day. At some point in the night, Mason entered the Spire and was met with "otherwordly screaming", likely from either the souls trapped on the Lunar Children servers or from the possible events that occurred earlier. Either way, Mason activated the detonation sequence on his device, and eventually destroyed the Spire.
Though Mason's actions were the most direct cause of the Cataclysm, it is possible that other factors were in play. One surviving Lunar Child attributed the events to them making some "very important people very angry" by failing to capture Tyler. This, alongside Doug's claim that Luna was to "feed", the growing Tenebris worship in the cult, Mat and Hunter's survival, and Patrem being "sucked into" somewhere, possibly implies that Tenebris also had a part in orchestrating what occurred.
