[DL] Sure it's Evil, but what's it Do?

["Tabb, David" <david.tabb@msfc.nasa.gov>]

I've got this idea for something evil for my posse to confront, but I'm
having trouble fleshing it out.  I hope you guys can help.  Potential very
tiny spoilers ahead.

Here's the deal.  News comes from someplace like Wyoming or Idaho that five
priests in five different towns have been ritually slaughtered on the night
of the 1st-half moon, ten weeks before a lunar eclipse.  All were killed the
same way at roughly the same time.  The towns were each about a day's ride
from each other.  If plotted on a map, the murder locations make a nice
perfect pentagon.  

Two weeks later (full moon), it happens again, in a different general area
north-northeast of there about 9 day's ride away.

And again two weeks after that (last half moon), southwest of the second
location and northwest of the first.

I'm sure you get it by now.  Someone is drawing pentagrams using the
sacrifice of a Blessed at each vertex, and drawing a larger pentagram using
the smaller ones as vertices.

The problem is this: why are they doing it?  Sure, slaughter of the holy is
fun, but they're obviously up to something more.  I figure there are three
basic purposes of a pentagram (this is the Satanic type, BTW, vertical point
pointing south): summoning something, imprisoning a summoned creature, and
protecting those inside from evil things outside.  I don't think the third
one seems appropriate, since killing priests to make a Satanic symbol
doesn't go with the idea of protecting large swaths of land from encroaching
evil.  Also, I don't want them to be making a Deadland, because that's been
done in one of the published adventures, on a smaller scale.  Although the
Fear Level will skyrocket as the murders continue.

So, I ask you of the list, what could be so evil and so large and/or
numerous as to require a state-sized, Blessed-blood-soaked pentagram to
manifest in, and yet not be the Reckoners themselves?  And who would be up
to something like this?  Could be a random cult, or the Mormons, or the
Angels, or voodooists, or Aztecs, or Shriners, Masons, hucksters, Rebs,
Yanks, the Red-Headed League, Thugees, a bunch of dumb kids with the
Necronomicon, the French, Dr. Miguelito Loveless, anybody.

David
(For any keyword-sniffers that may be out there, this refers to a GAME.  I'm
not really plotting the deaths of 25 actual clergymen.)