Final answer:
Loki transformed into a mare and lured the stallion away to prevent the mason from getting his pay.
Step-by-step explanation:
In Norse mythology, when the gods were building a wall around Asgard, they made an agreement with the mason that he would receive his pay if he finished the job within six months. However, the mason was close to completing the wall with the help of the stallion Svadilfari. Loki, wanting to prevent the mason from getting his pay, transformed himself into a mare and lured the stallion away, delaying the completion of the wall.
Learn more about Norse mythology