In order for Clan Daupuz to survive, they must escape the fjord, which is far more difficult than said.
Their ships were badly damaged by the raid of undead and magic, They would barely make it from the island back to the coast with the ships to repair them. If that were not a struggle enough, the power of the old gods made the mountains enclose the fjord and have erected a kind of dome which prevents any from entering or leaving the fjord who does not have the power or will of the old gods themselves.
In short, Death Bringer, which has the old god’s essence imbued within it, can act as key and allow the Vikings to leave the fjord if they can steal the axe back from the Cult.
It is known from the past days of the cults of the old gods that those cultists could also shape-shift their appearance. So there may even be some of them wander through the ranks of Clan Daupuz, ready to sabotage any chance of survival. All that remains for Clan Daupuz is the hope to restore their ships, survive the onslaught, defeat The Betrayer, and reclaim Death Bringer.
