Werewolf the Apocalypse Rage Across St. Louis
The Delirium is an effect of human race memories of the Impergium, when they were ruthlessly culled by the Garou. Some other Fera also cause a similar effect, either because they resemble the Garou, or because they too committed slaughter of early humans.
Delirium 69, 262-263
effects chart, 263
see also Veil, the