Each individual Demon has its own unique shape and appearance. Some appear as glowing balls of flame, while others take the forms of grotesque monsters. A few are shapeshifters.
Demons have a natural resistance to magic and even the weakest are capable of countering minor spells. In addition, their nature allows them to manipulate magic against their enemies.
Demons are creatures of chaos, unloyal to any beings or forces other than their own twisted desires. They exist purely to cause mayhem and anarchy. Most are sapient, if just barely. Demon Lords are the exception in being highly intelligent.
Demons are jealous of all material beings, constantly trying to access the physical world and enjoy sensation. They seek to kill, murder and destroy, simply to cause chaos that will overthrow the beings which have such a life as they wish for.
Demons, like the Gods, are formed from the primordial ether of the cosmos. They vary greatly in power due to variations in the size of accumulations, but none reach god-level size in the modern day.
Dark Wizards are capable of summoning Demons into this dimension. They do this in the hopes of controlling the creatures; however, the Demons most often eat the Wizard and then go on a murderous rampage across the known world. The Summoning of Demons was banned from Emiria in the year 2695.