The Cataclysm

Overview
The Cataclysm is the apocalyptic event that ends The First Aeon of Studio Arctica. The event is caused by an epiphany of The Host while he and Chad work on the third season of the sitcom, and is told through the story of Season 3 of How To Make A Sitcom. The Cataclysm results in apocalypses in varying forms for all major characters. It is described in The Book of Arctica.

Apocalypses
In order of happenstance:

The Cataloger - The discovery and initial possession of The Timber Ghost

Steph Rickerson -

Pharstle MacMcMillion - The discovery of his existence as The Narrator and The Motherbrain

Arctica - Becoming "unplugged" by Pharstle/The Motherbrain (death)

Chad - Shot and killed by Steph Rickerson

The Host - Imprisonment in The Bear Cave

Edgar - Becoming the second Arctica | fills the space left by The Host

The Writer - Awareness of The Reject coming out of The Maw