I suggest something like a band of rangers and barbarians who have revenge as their organizational goal. For most people they are viewed as evil or dangerous at the least. In the strip a young boy blows a horn to summon one who battles a beast that killed his friends. That is interesting, but it stops too short of resolution. Maybe blowing the horn has a price of entry into the organization and the horns are placed in every town or holdfast. Everyone warning against using the horn but keeping them as the Hollow Reeds kill off a number of monsters and animals.
The big thing is they become lame if they are misunderstood good guys. We have to make them complicated and dark in nature. Perhaps they are willing to do whatever is needed without concern for hurting people when they are pursuing their goals. Also they are a secret society that does not allow others to see their members, killing off those who stumble on their camps and taking children for work. Girls could be carted off as wives for the leaders or leader they may be Mormon.
The plot hook could be something like parents trying to get back their children that have been taken and paying the party to save them. The party then deals with an enemy that may not be as evil as they thought but still has fangs and is unwilling to let the children go as they know the members of the Hollow Reeds. Some members could be members of the town whom wish to remain unknown members of the Hollow Reeds.