Timeline

A timeline is a single and unique chain of events. It may or may not be very similar to other timelines, but will never be exactly alike across time.

Balance
The balance of a timeline refers to the relative distribution of essence among the population. The less balance a timeline has, the more likely it is to have powerful magic users and to have everyday life affected by magic.

Stability
The stability of a timeline refers to the frequency of "natural" disruptions of the laws of the universe. If a timeline is ever classified below "normal", its stability will only grow worse until it completely passes from existence.