Demons are the physical manifestation of raw chaos. They are not pre-existing creatures, but rather spawn whenever sufficient chaos is found in a system. You can conjure one from thin air.

Choose a creature with the Demon and Regular properties. It appears in a square adjacent to you.

When you initially summon the Demon, and every turn when you Sustain this Spell, the demon will choose a random target, move up to twice its speed towards that target, and attack it. It chooses its target randomly, with the only limit being that the target must be hostile towards you. It does not consider attacks of opportunity or flanking; it never Steps or Shifts, and always moves to the closest square to its initial position, from which it may attack the new foe. You have no actual control over the creature as it tears around the battlefield, attacking random targets until destroyed or you allow it to vanish.