In Norse mythology’s Ragnarok, Heimdall blows the Gjallarhorn to announce the battle. Heimdall is the vigilant god who guards Bifröst, the rainbow bridge connecting Asgard and the human world. His exceptional hearing and sight make him the ideal watchman for the gods.
The Gjallarhorn is a famous horn associated with Heimdall. In the account of Ragnarok, its sound signals the gods and their enemies that the final conflict has begun. The horn is also linked with Mímir’s well in some traditions, so it should not be confused with an ordinary battle trumpet.
Heimdall and Loki are destined to kill each other during Ragnarok. This final duel helps distinguish Heimdall’s role from Odin’s: Odin leads the gods but does not blow the Gjallarhorn. Modern retellings sometimes give the horn to another god, but the surviving mythological tradition assigns it to Heimdall.