It is set 35 years before Final Fantasy XV
The Empire of Niflheim researcher by the name of Verstael Besithia has released Ardyn Lucis Caelum from 2,000 years of imprisonment. Ardyn later found out certain truths and decided to bring vengeance upon the Kingdom of Lucis. New systems will be used uniquely to Ardyn who possesses Daemon powers as well as transforming enemies into one called “Daemonification”.
Final Fantasy XV “Episode Ardyn” expansion will launch for PlayStation 4, Xbox One, and PC on March 26, 2019.
Additionally watch the Final Fantasy XV: Episode Ardyn Prologue anime below: