Tarnhelm

Origin
Composer Richard Wagner's “Der Ring Des Nibelungen” (The Ring of the Nibelung), loosely based on Norse sagas. Crafted by Mime for his dwarf brother Alberich, he used it protect the treasure of the Nibelungen.

Effects
When worn, it allows for teleportation, shape shifting and invisibility. However, it marks the user for death at the hands of their lover and causes them to sing only in opera when in use.