I'm creating a new space marine list at the moment based off my own chapter fluff, their called the WILD DOGS and are raised from the FOX archipelago of islands on a death world.

For their leader I want a captain who is aging, was once a great Marine but then took retirement sort of thing, then comes back for a final mission as all his old buddies need his skills on a crusade. He's an expert at combat and stealth.

The company he leads will be based more around stealth, so i want them to be a drab sort of blue colour, with their body armour filed down so it looks more like a sort of 'sneaking' type of suit. They will be armed with a variety of weapons from different races because they take their weapon from dead enemies and use them.

I want them to be a bit rough around the edges, so I'm going to model some of them smoking, which isn't really in keeping with the mainstream fluff but will look cool.

What I need for them is a quest, some sort of goal for a crusade. I don't really want to use the generic nids/chaos/orks threats, does anyone have any ORIGINAL ideas on what they could focus a crusade on?