The creature is a kind of vampire, but it doesn't suck blood. If I recall correctly, it somehow attracts blood to it as if by a powerful magnetic force, the blood splatters on its body and is absorbed through its skin. I don't remember if it has to tear its victims bodies, or if the attraction can be so strong as to pull the blood out of victims who stray too near.
Does this ring any bells? I'd love to find out what it was called and where it was written up. I could just make it up, of course, but some of the fun of this game is going to see if the players can figure out what system/universe/book any particular thing comes from. For that to be fair, I need to base it on more than just a vague memory.