For
 10 points, name this eight-legged horse of Odin.
The kenning for Baldr's funerary boat contains the name of this figure, whose descendent Grani is a
 companion of the hero Sigurd. In the Prose Edda, Gangleri is told how Thor bet Hrungnir that this figure
 was superior to Gullfaxi. He is born after the gods wager the sun, the moon, and Freyja against a builder's
 ability to build Valhalla without another man's help. The builder makes incredible progress with his animal
 helper Svadilfari, so Loki seduces Svadilfari while disguised as a mare, later giving birth to this figure. For
 10 points, name this eight-legged horse of Odin.
The kenning for Baldr's funerary boat contains the name of this figure,
Sleipnir