For 10 points, name this guardian of Bifrost who will blow the Gjallarhorn to announce Ragnarok.
One grandson of this deity is Kon the Young. This god was once wounded by a thrown severed head, leading "head of [this god]" to become a figurative phrase meaning "sword." He transformed himself and hid among seals to recover a magic necklace and is conflated with a deity who slept with three women to father the first thrall, peasant, and noble among mankind in the form of (*) Rig. This deity owns the sword Hofund. This gold-toothed rider of the horse Gulltoppr is the son of nine mothers and is able to hear grass grow. For 10 points, name this guardian of Bifrost who will blow the Gjallarhorn to announce Ragnarok.
One grandson of this deity is Kon the Young. This god was once wounded by a thrown severed head, leading "head of [this god]" to become a figurative phrase meaning "sword."
{Heimdallr} [accept {Rig} until mention]