Age of Satan
From Satan Service
Whether in Latin ('Anno Satanas', 'AS') or in English (e.g. 'Year of the Adversary' for those who don't personify Satan), this represents a personal magical 'aeon' or 'age' signifying theme, influence, and suffusion associating to the God of This World.
Since it is personal, rather than astronomical or astrological, it may be characterized as an aeon, and will be particular to some individual magician as to its exact timing. The notion of personal 'ages' was popularized by Aleister Crowley, and in association with Satan and a temporal scheme, by Anton LaVey.