Comet

A comet is a celestial object generally seen as a sort of sign of doom.

Description
In the population, the belief was held that comets were signs of impending doom. The Avatar learned there was something to it when using the spyglass in Ultima V. As it turned out, a comet seen in the night sky over any planet of the Britannian Solar System meant that the city associated with the same virtue as the planet was under attack from one of the Shadowlords. This allowed the Avatar to avoid those cities until the shadowlord had left.

These comets were never again observed after the destruction of all three Shadowlords.