This is decidedly an adventure for a powerful adventuring party. It starts off simply - a werewolf on the loose, but there's potential for almost open-ended levels of pain if several more Leádstæf escape.
When you run this, consider letting the players get stuck in before the Vinteralf arrive. The hermit, the ghost, and the members of the circle are all potentially friendly, at least initially, and Hyngran has plenty of destructive potential, especially if a PC or two gets bitten.
It's important not to play the Vinteralf as if they're here to save the day while the PCs watch - they're not! They're meant to be potentially sympathetic antagonists: they start out rather pathetic, and perhaps they solicit the party's help in finding the hermit. Perhaps the party discovers them incapacitated with fever. And after all, they're trying to save their homeland from the Leádstæf.
Once they get rolling, however, they're extremely destructive. They're not above befriending the party and turning on them once they have what they need. Remember that they've given up everything they care about to come on this mission, they're not going to get squeamish about a few blubberless southerners. Or will they?
Once more, thanks to everyone who's been supporting this project, it's been really fantastic.