Thanks for the suggestion--but I didn't find anything there.  Of the mobs I mentioned the only one that had anything that might seemingly be related was Naggy:
sub EVENT_SPAWN {
  my $x = $npc->GetX();
  my $y = $npc->GetY();
  quest::set_proximity($x - 250, $x + 250, $y - 250, $y + 250);
}
sub EVENT_ENTER {
  if (($ulevel >= 53) && ($status == 0)) {
    quest::echo("I will not fight you, but I will banish you!");
    quest::movepc(27,-64,262,-93.96,0);
  }
}
sub EVENT_AGGRO {
  quest::settimer("getloc",15); #mob will get position every 15 seconds if pulled away from spawn point
}
sub EVENT_TIMER {
  quest::clear_proximity();
  my $x = $npc->GetX();
  my $y = $npc->GetY();
  quest::set_proximity($x - 250, $x + 250, $y - 250, $y + 250);
}
sub EVENT_DEATH {
  quest::stoptimer("getloc");
  quest::clear_proximity();
}
Specifically the Sub_event SPAWN stuff.  I dont' see any sort of timer though (and he doesn't auto-repop on server reboot).  I think more likely that's just a range for the banish.  I also went through the rest of the quests in soldungb and came up with nothing.  Likewise, I checked out KaranaEast (for quillmaine), and FearPlane (for Cazic), and got nothing there either.
Thanks again for the help, but it appears I'm still looking for the answer...