Short answers, pulled from the story.
The Galdrabók is an Icelandic grimoire dated to around 1600. Its name means "Magic Book," and it is a small manuscript containing forty-seven spells and sigils compiled by four scribes, with work possibly beginning in the late sixteenth century and continuing into the mid-seventeenth.
Four people compiled the Galdrabók. The first three scribes were Icelanders; the fourth was a Dane who worked from existing Icelandic material. No single author is identified.
The Galdrabók contains both protective and harmful spells. Protective spells address conditions including insomnia, headache, trouble with childbearing, pestilence, and distress at sea. Other spells are designed to cause fear, find thieves, kill animals, put someone to sleep, or bewitch women.
The spells in the Galdrabók draw on Latin, runic writing, and Icelandic magical staves. They include invocations to Christian figures, demons, and the Norse gods, as well as instructions for the use of herbs and magical items.
Stephen Flowers published the first English translation of the Galdrabók in 1989. Flowers produced a corrected second edition in 1995 with the assistance of Sæmundsson, adding more notes and commentary.
The Jarðskinna is a small Icelandic grimoire that had not been published before 2024. Icelandic folklorist Kári Pálsson included it alongside a new illustrated English-Icelandic edition of the Galdrabók in that year.