Heimdall's Horn
From AmtWiki
This rule is outdated
a Relic
A one handed ‘red’ weapon only usable by Barbarian, and in fact, the only rulebook relic allowed to barbarians.
In the 6.0 Rulebook, this relic was known as Odin's Hammer. Different name, same effect.
For More information check out the Rulebook section on Amtgard Magic