Vedrfolnir is a giant bird from Norse mythology. Claim his tile and heal him will grant you lore and he will scout new tiles for you before leaving northguard.
Vedrfolnir can possibly spawn on the same tile as the wyvern.
Vedrvolnir is encounter in chapter 11, crash-landed as result of its sense disrupted by Gjallhorn's sound. Recognizing the mythical bird, Rig secured the area around it and have his healers tending its wounds.