Some of the nearer undead start to lurch towards the group as they are revealed, but after its been confirmed that you're all together, the imp yells "Hey now, back to work, don't do that!" and they return to their labors. Its obvious that protecting the site from the living is some part of their job, because the imp waves several others back as he speaks. "I'm not supposed to leave this area, gotta keep a lookout, you know, make sure no one interferes. We're on a timetable here, and the Master can't bring in any big guns until the tower's set. You could help with the foundation, or help me keep an eye, or maybe the Master wants some backup at the seed."