The only guaranteed way to get the items you need to unlock a Varwolf is to play through the questline associated with them. Otherwise you will have to check the Shop Wizard, Trading Post, Auction House, etc. to find and purchase them. But we hear there’s another way, if your eyes are sharp and you search the Haunted Woods thoroughly…
The Map Pieces needed might be granted through random events or other site features, too. Keep an eye out for opportunities to get them!