Nightmare sent his group of demons - Killer, Horror, Dust, Error and Cross to watch the angels in order to find a suitable day to attack the angels.

Killer, Error, Cross, Dust and Horror with wings (similar to the wings of a bat), with a demonic tail and horns. They hid behind the clouds, flapping their wings to stay in the air, trying to find the angels, or at least an angel.

Killer: he's playing with his knife, looking around for any sings of angels.