Grugnur was once the jarl of the Iceblood clan of frost giants. Lairing within a glacial rift high in the Iron Crags, the giants frequently raided the nearby Iron Skull clan of barbarians.
In the year 2959, he formed an alliance with the Prince of Frost for unknown reasons. Soon after, he ordered his giants in a massive raid on the Ice Skulls. Though they were ultimately repelled, they succeeded in slaying the barbarian chieftain Torgar Beornagar and claiming his greataxe, Wintersbite. In response, the new chieftain Alae asked the Challengers of the Unspeakable to reclaim it. Posing as eladrin diplomats, the Challengers infiltrated the rift with little difficulty and slew the chieftain in his own chamber.