Hercules and the Twilight of the Gods

Hercules and the Twilight of the Gods is an episode of Hercules: The Animated Series.

Summary
While training with Phil on how to fight giants, Hercules is offered a temp position with the Norse pantheon by Loki as a new Thunder God when Thor is unable to perform his duties. But Loki is planning to use this opportunity to begin Ragnarok and awakens Fenrir and the Frost Giants to attack Asgard and the gods. Hercules must stop Loki, stop the coming of Ragnarok and save Thor and Odin.