Old Norse shamanic magic used to perceive and shape fate.

Seiðr is a form of Norse magic closely linked to fate and the hidden. The practitioner, often a völva, entered a trance-like state to travel between worlds, prophesy the future or influence events.

Seiðr was considered ergi, that is, unmanly, for male practitioners, a taboo that Óðinn nevertheless transgressed. Freyja is said to have brought the knowledge to the Æsir, and there are connections to Sámi noajdie tradition.

Attestations

Eiríks saga rauða, kap. 4
Classic description of a völva's seiðr ceremony.