– A stag residing in Hotel Valhalla. It constantly pours water into a lake, which serves as the source of all water in the Nine Worlds. Fenris Wolf – The lupine son of Loki and the brother of Hel and Jormungand. He was a terror in times past and the gods could only chain him up with the help of the dwarves to stop him; even Tyr had to lose his hand against the wolf, while Blitz's father, Bilì, lost his life while checking his prison on Heather Island. During Ragnarok, Fenris Wolf is destined to kill Odin and eat the sun. He is the focal point of The Sword of Summer, as the goal of Magnus and his friends is to stop Fenris Wolf from breaking free of his prison, which needs to be rebuilt. They manage to imprison him again at the end of the book. Geri and Freki - Odin's two wolves who act as his representatives. Their name means either "the ravenous" or "greedy one". Heidrun – A goat whose milk is the source of the mead that serves the gods. Like Eikthrymir, Heidrun resides in Hotel Valhalla. Huginn and Muninn – Odin's two ravens who act as his spies as well as representatives in giving missions to his special aides, such as Sam, when he is not around. Their names mean "thought" and "memory", respectively. Helgi specifically notes that the two do not like to give PowerPoint presentations, unlike Odin. Jormungand – The serpentine son of Loki. He is a snake who circles over Midgard and is so long he must hold his tail in his mouth to prevent destroying Midgard. He is lured by Magnus and Sam to cause a ruckus in the sea big enough to summon Ran. Even after being lured, Jormungand is still half-asleep, but Ran warns that waking him up completely would cause Ragnarok, where he is destined to kill Thor. Lindworm – Large, fearsome dragons with bat wings who reside at the roots of Yggdrasil. One of them is sent by Loki to catch Magnus and his friends during a Valhalla training off-guard. Nøkk – Water spirits who play sad music through violins, sending its listeners to despair. In The Hammer of Thor, Alderman summons a horde of Nøkk to attack his guests and Magnus and company. Otis and Marvin (Tanngrisnir and Tanngnjostr) – Two goats who pull Thor's