Exactly what it says on the tin. I need help building a monster.

Deets:
This is all Deadlands setting- 1876 wild west with magic and horror.

Mad scientist captured monster, knowing it shies away from both bright light and cold. Said scientist has a failsafe to release the monster if he ever gets killed. Assassins killed scientist, monster is loose.

Sitch:
I want the PC's to chase the monster, but in no way be able to hurt it / catch it without using the light guns they'll eventually find. The monster shouldn't be a 'hulk smash', because, knowing my PC's, they'll just try to physically overpower it. I was thinking a living shadow that can possess people, but the 'you must fight your party member' thing seems a bit trite. I need something untouchable, but still very dangerous.

Any help would be, well...helpful!
This message was last updated by a moderator, as it was the wrong forum, at 19:12, Thu 11 Sept 2014.

A Frankenstein's Monster with six arms and six six-shooters.  It's so dense that it is essentially immune to bullets, but its tender albino flesh is combustible in the Sun.  Though physically powerful it is also very intelligent and only fights battles it knows it can easily win.  It frequently flees from Foes and lies in ambush before fleeing again.

As it learns and grows accustom to the world it begins to take an interest in making something of itself.  Perhaps it joins up with another Mad Scientist as a Henchman or becomes a behind the scenes schemer / foil for the Party.  It could call it's self "Mr. Graves" or "Mr. Tombstone" or something.

 Monstrous liquid: It can get in and out of any tight spot, can take the shape of any of your members and toy with them to lure them to...fear, which it feeds on, quite literally, the hormones and brain chemicals it needs. So it will try to scary the crud out of the party before closing in. Cutting it up only creates a new blob of smaller size.

 or

 Plaguebeast: It carries a toxic chemical or contagion that begins to subvert the tissue of other creatures, ala the Thing. So it will replicate if it can infect team members and either mutate them grotesquely into another version of the monster or the infection serves to 'digest' the team for easy feeding. In the desert setting of deadlands this would be cool to unleash on a small oasis without fear of having this thing spread across the whole setting. Nice little scary story arc.

 or

 (in the theme of deadlands)
 Carrion Crawler: A smooshy twist on the old DnD version. This thing wants bones and will eat them in a living body if it can. It's insectoid and extremely fast(so it's difficult to overwhelm with slow brutes), and it's like a big cockroach so it hates light. It possesses tentacles on it's head that produces a anesthetic quality so you can't tell if you've been attacked until you see(perception check) it. BOnus, you can leave a scary trail of bodies it's already taken the bones from to tease your party.

The living shadow idea sounds pretty cool (minus the possession bit). Maybe it has a physical body but that's relatively small and at the core of a swirling mass of shadows, and the creature can therefore hide pretty much anywhere vaguely dark by just blending in with the shadows or standing in a corner and pretending to be a shadow. Bright light can pierce through the shadowy outer veil and reveal the creature within, which itself fears the light and can be easily dazzled/hurt by it, which is why it shields itself in shadow. It hunts by just standing still in a spot where it culd conceivably be just a normal shadow. Until its prey gets too close, at which point it reaches out with shadowy fingers and, lightning-fast, grabs its prey, dragging it inside the shadow to consume it. Exactly what the creature looks like can remain a mystery, all the more to be scared of it :D.
Maybe the shadows dull any sound within, so the screams of any victims will go unheard (or at least be severely muffled, as though their face was covered by a very thick pillow or similar). And maybe this creature consumes its victims utterly, leaving no trace and that's what makes it even more scary - did Bob jst leave the room for a moment with no-one noticing, or did he just get eatn by that shadow over there that you're not entirely 100% certain was there five minutes ago?
Anyway, the creature can run super-fast if it has to, but if it's hunting it needs to stand still for maybe a minute or two to sort of "prepare itself" or whatever. This way it at least can't zip around insta-killing people or whatever, but can still get itself out of trouble if attacked ;).

Maybe some sort of living sand monster- it lives underground in the desert, and only emerges at night. Combine that with the legend of the hydra- the PCs can try to fight it, but they'll just end up fighting two or more unless they use the light guns.

Something like a living stone? Or a creature that can at least disguise itself as a large stone?

A germanium golem.

A creature of dark fire/dust. Looks like a cloud of floating slightly burning embers. Likes deep dark caves. Hurt by UV so only sunlight and special light hurts, while lanturns etc don't bother it.

Old West. Hates cold and sunlight. Make yourself a Gila Monster, grown to gargantuan size with some steampunk/cyborg attachments. Retains the flavor of an Arizonan monster.

Sounds like you need Dr Who's Vashta Nerada...

http://tardis.wikia.com/wiki/Vashta_Nerada

Have fun. :)

 Sometimes I wish we had a karma system on RPoL. I'd +1 that.

Thanks! I am going to do a full write up on it at some point. :)

 Awesome, there are lots of good ideas here but that one's my favorite to visualize.

This message was deleted by a moderator, as it was against the forum rules, at 07:58, Tue 23 Sept 2014.

This message was deleted by a moderator, as it was moot, at 07:59, Tue 23 Sept 2014.

You could go with a liquid terminator vibe mostly unstoppable unless you were to fry it with an emp (the light guns) or freeze it solid and keep it that way. it could also serve as the escape mechanism if the scientists power goes out (from non payment) then the fancy freezer won't hold it anymore

The very slightly material shadow thing, when it possesses a PC, doesn't want to kill anyone. It just wants to stay in the warmth and darkness of its host, who may not even be aware of it at first.

However, it interferes with the host's absorption of nutrients and the host slowly starves to death over the course of a couple of weeks. The entity then must find a new host.

It cannot absorb nutrients from the host, but leaves the host at night to hunt the darkness for small prey, draining cats, rats, dogs of their moisture and life, leaving dry husks. As it grows in power and size (a matter of some days or weeks), it may begin preying on children.

After a month or so, it will bud a new organism, which then must find its own host.