If Vallus is back, then we haven't much time. The Rath'een that summoned him clearly have no idea just how dangerous he is, and if we don't cut off his power soon, this whole land will soon be covered in ice. In the tomb where his body rests is an army of Snow Sentinels. If we can slay enough of them, we may be able to maintain the element of surprise going into Vallus' lair.
Slay 10 Snow Sentinels in the Tomb of Vallus within the Frozen Vale: 0/10
I know what you were thinking in there - why not just destroy Vallus' tomb? Unfortunately, Vallus live on as the dreaded ice dragon we've spotted flying over the Vale. If we're to stop him, we need to enter his lair and strike him down together. I will summon you when the neccessary preparations have been made.