Nachtmagen

""It's the fyngrot!" Did he shout that or did someone else?

Coryn realized what was happening. He was more frightened than he had ever been before. He could taste the bile of his fear. He could feel his muscles locking. He began to stagger in flight.'"

―Coryn's description of fyngrot, The War of the Ember, page 215

Nachtmagen is an evil form of magic that primarily 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 or plucked eyes. 

Known Spells

Fyngrot

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.

Exceptions include Queen Siv, her son Hoole due to their strong Ga, and the wolves from Beyond the Beyond due to the power in their eyes to combat the nachtmagen.

Nacht Blucken

Powerful hagsfiends such as Kreeth can use their powers to create new, hybrid species of birds from unborn eggs, but preferably hatchlings, with Lutta and the Puffowl as notable examples. This spell is cast in two parts, the first being a poison resistance spell that is spoken while the subject is surrounded by half-hags. The second part involves plucking out one of the eyes of the subject, allowing the nachtmagen to enter through the empty eye socket. This eye will grow back when the transformation is complete.

Dream-sight Divination

Kreeth was able to enter Hoole's dreams while sleeping by placing a withered gizzard into a solution and speaking this chant perfectly:

"Veeblyn spyn crynik spyn veeblyn Hoole Elooh nylbeev nyps kinyrc nyps nylbeev."

―Kreeth, To Be a King, page 120

Shapeshifting

Some hagsfiends from the past, such as Ygryk, could shapeshift into owls using a temporary spell. There is also a species of hagsfiend created by Kreeth, known as changlings, that could shapeshift at will into any bird. The only known example of such a hagsfiend is Lutta.

Divining Eyeball

A spell can be cast upon a severed eyeball to create the ability to see visions within it, similar to firesight or starsight. The eyeball is cast onto an ice pyramid stand, where it is suspended above, presumably by the spell. It begins to slowly turn, forming images from sparks of gold. After a vision is seen, the eye must recover its sight and cannot be used for several days. Kreeth makes one such Divining Eyeball with the eye of a Barred Owl, which she claims was hard to find because it had to be "just the right one." She uses it to spy on Mycroft.

Other Species with Nachtmagen

Owls - Capable of using nachtmagen, owls that surround themselves by hagsfiends and/or practice the magic will be affected by it, their feathers slowly appearing more haggish, or black and raggedy.

Vyrrwolves - Dire wolves who drink from the pool in the Tunnel of Despair can be infused with nachtmagen. Their power and size depends on the phases of the moon, being their most powerful and largest at full moon and weakest during the new moon. They are capable of casting fyngrot.

Dragon walruses - An ancient, extinct species of sea monster from long ago, dragon walruses are spawns of nachtmagen that are capable of breathing fire. They are only mentioned and appear in Bears of the Ice.

Frost vipers - Nachtmagen-spawned serpents created by hagsfiends, frost vipers are considered still-living remnants of the hagsfiends' nachtmagen. They are shadowy black serpents with glowing red eyes, and a single bite to a mammal will cause immediate death. They travel in "slithers," large groups of up to one thousand snakes, which don't pose a threat until one snake breaks loose from the pack. They reside only in underground tunnels of the Northern Kingdoms.