Daemon (Final Fantasy XV)

Daemons are nocturnal monsters in the world of Eos in Final Fantasy XV. It has been said that daemons have become more common lately, and some speculate it is because the nights have lengthened. Daemons don't appear in Insomnia because of the barrier upheld by King Regis Lucis Caelum CXIII.

Daemons are modeled after recurring enemies from the Final Fantasy series, and often have an otherworldly appearance in juxtaposition to the wildlife monsters fought during the day.

Brotherhood Final Fantasy XV
A young Prince Noctis was once attacked by a Lamia that killed the woman who was minding him that day. He was saved by his father, King Regis, who had driven the Lamia away as it had fallen off a cliff. Noctis was badly hurt and fell into a coma. After the king sends Noctis out to marry Lady Lunafreya Nox Fleuret, they are attacked by the Niflheim Empire while on the road, and an imperial airship drops a container that releases the Lamia Noctis recognizes from his youth. Concluding that the Lamia that attacked him as a kid was sent by the Empire, an enraged Noctis engages the daemon and emerges victorious with his friends' help.

Kingsglaive: Final Fantasy XV
The Empire is sending out daemons to battle the Lucian forces, among them being the colossal Diamond Weapon whom Nyx Ulric's team has to fight. After the Wall around Insomnia falls, daemons spawn within the city itself, destroying everything on their path.

Gameplay
Daemons appear on the field during the night. If daemons come onto the roads while the player is driving, the party will stop and get out of the car to fight. Daemon are stronger and fiercer than monsters that appear during the day. If the battle against a daemon draws for so long the sun rises, and the daemon starts taking sunlight damage.