Winterskorn clan (or tribe)  is a clan of  vrykul that live in Skorn and Baleheim in Howling Fjord of Northrend. They are led by Bjorn Halgurdsson. The elders of Winterhoof tribe say that these vrykul may be able to rise from the dead; not unlike the Scourge, but a different kind of undeath.
Thousands of years ago, armed by the
fire giants Volkhan and Ignis, the Winterskorn attacked other titan-forged across the Storm Peaks, thus beginning the Winterskorn War. They caught the attention of Tyr when they attacked the earthen. Tyr asked the Dragon Aspects for aid, and the war ended with Ysera and Nozdormu putting the Winterskorn into a timeless sleep beneath northern Kalimdor.
The Winterskorn were awakened thousands of years later by the
Lich King to serve the Scourge. They answered to the Dragonflayer clan.
Fights in Baleheim
The camp fights
The Hand of Vengeance, many vrykul are killed at the request of Sergeant Gorth and many buildings are burned. 
Bjorn Halgurdsson, their leader, was killed in a trap by Forsaken.
Skorn must fall
The vrykul intend to strike the
Camp Winterhoof. The Chieftain Ashtotem have to buy times to leave in the north in sending Winterhoof Brave strike in Skorn. They set ablaze any buildings as Northwest Longhouse, Northeast Longhouse and Barracks.  They dismember any corpse to prevent any resurrection.  The Tower keep has been destroyed by airstrike. 
humans from Valiance Expedition have the same goal in Skorn.
During the fights in Skorn,
Halfdan the Ice-Hearted has been killed to prevent his ascension.