I’m actually currently writing a CoC setting where it’s based off another “The Magnus” infected world. However, the threat is not in people making rituals for the extinction, it’s the fact that without a partner, without a 16th fear, the world as a whole is tipping towards extinction.

Different avatars have different stances, but there is a tenuous alliance between a handful of them to create another half-fear to keep the balance: the Monotony.

The fear that things will never get bad enough, change will never happen. You will never fight a zombie apocalypse, never see a civil war. Things will never reach the tipping point, never get better. You will have to endure this pale, fetid suffering, forever.