I tried it out and really like the concept, but it seems like there's way too much luck involved. If you can't address more than one monster at a time, I don't see how the player is supposed to survive a situation where two of them show up at once. You choose one to focus on and while you're waiting for it go away, the other attacks.
Well, that's a start, but once you make it further into the night there's a possibility that all three show up simultaneously. At the point, even if you have the shock available, you're still screwed because you'll have two of them in the room. Obviously, whichever one you're not paying attention to ends up getting you.