Loki and Svadilfari2 by Hellanim.deviantart.com on @deviantART The Builder was contracted to build the walls of Asgard, with the help of his horse, Svaðilfari. If he could do it in a year, he'd get the sun, moon AND the goddess Freya. When it became apparent that the builder was a Jotun and fully capable of completing the project in a year, the Aesir began to worry. It fell to Loki to solve the problem. So Loki transformed himself into a mare to distract Svaðilfari.