For 10 points, name this husband of Sigyn and Norse trickster god.
Some of the medieval sources about this god may have plagiarized his tales from the Cycle of the Narts, an Ossetian epic which contains the very similar figure of Syrdon. He gave a gold-seeking ring to Hreidmar after stealing it from Andvari. In the Poetic Edda, this figure is invited to a feast given by Aegir, the sea god, but he loses his temper, kills a servant, and is driven off. The son of the giant F?bauti, this figure who will be killed by Heimdall at Ragnarok himself fathered Hel. A giant with the ability to change shape at will, he uses his powers to give birth to Odin's horse, Sleipnir. For 10 points, name this husband of Sigyn and Norse trickster god.
Some of the medieval sources about this god may have plagiarized his tales from the Cycle of the Narts, an Ossetian epic which contains the very similar figure of Syrdon.
Loki