"It's the fyngrot!"...He could feel his muscles locking. He began to stagger in flight...
- Description of fyngrot, one form of nachtmagen
Nachtmagen is an evil form of magic that Hagsfiends have access to, and use in a variety of forms.
It was used by the hagsfiends even since the time of The Legends of Ga'Hoole, and was declared a plague to the world since them.
Many Nachtmagen spells involve dark rituals that need many sinister objects to occur, like the cinders of dead owls.
One of the most known types of Nachtmagen, the fyngrot is used in battle to paralyze and hypnotize foes. Most creatures cannot easily resist this spell without external aid.
Using chants and potions, Kreeth was able to enther Hoole's dream while sleeping.
Some hagsfiends from the past, such as Ygryk, could shapeshift into owls using a temporary spell.