There is a special form of bifrost crystal the Jotnar gifted to those they trust, a pair of magic eyes. These eyes functions best as a pair and capable of being used to project images and a replacement travel crystals, as it can refract the energy like a travel crystal, although one said that such use leave the eyes-holder feeling unpleasant.
In Norse mythology, Bifröst ( or sometimes Bilröst or Bivrost) is a burning rainbow bridge that reaches between Midgard (Earth) and Asgard, the realm of the gods. The bridge is attested as Bilröst in the Poetic Edda; compiled in the 13th century from earlier traditional sources, and as Bifröst in the Prose Edda; written in the 13th century by Snorri Sturluson, and in the poetry of skalds. Both the Poetic Edda and the Prose Eddaalternately refer to the bridge as Ásbrú (Old Norse "Æsir's bridge").
According to the Prose Edda, the bridge ends in heaven at Himinbjörg, the residence of the god Heimdallr, who guards it from the jötnar. The bridge's destruction during Ragnarök by the forces of Muspell is foretold. Scholars have proposed that the bridge may have originally represented the Milky Wayand have noted parallels between the bridge and another bridge in Norse mythology, Gjallarbrú.