Question: how to unlock hyjal summit?
Answer: Comment by 56164. Hyjal Summit is located in the Caverns of Time, it is a 25-man raid encounter. The optional attunment quest begins when you talk to Soridormi in the Caverns of Time, you then must get Two vials that drop from Kael'Thas from the Eye and Lady Vashj in the Serpentine Caverns.