Bloodman 3.0

Living masses of blood, broken bone and shattered organs. They appear as vaguely humanoid masses of crimson liquid with rudimentary limbs and heads that are little more than round extrusions with gaping holes where their eyes and mouths should be. 

Source: Creature Collection II: Dark Menagerie 3.0

Cool Factor: A humanoid creature made of blood. That alone is cool enough for me. It does have some pretty good mechanic behind it that makes it more interesting. The Bloodman is a medium sized aberration with the ability to assume a liquid form, duplicate itself, absorb hit points, and has some unique weapon immunities. They generally form colonies of 4 to 8. They have very low intelligence and make for a good random encounter or dungeon denizen.

Combat: The Bloodman is a CR 5 creature with relatively low hit points(avg 22 hps) and armor class(AC 16). It makes up for them with some interesting special abilities which I detail below.

-Steal Blood/Duplicate: Bloodman attacks are touched based. Each successful attack absorbs 1d4+1 hit points into the Bloodman. After absorbing 22 hits points the Bloodman can duplicate another 5HD creature within 1d4 rounds. If you are using a colony of them, then collectively they can sacrifice those absorbed hit points to create another of their kind.

-Liquid Form: The Bloodman can assume a liquid state. It retains all it's immunities and defenses but it allow them to double movement speed.

-Weapon Immunities/Vulnerability: They are immune to non-magical slashing & piercing damage, but take normal damage from bludgeoning weapons. If you have a magical slashing/piercing weapon the damage that is done is equal to it's enchancement bonus. A +1 longsword would do one points of damage, a +2 longsword would do 2 points of damage, etc. I haven't seen any creature that has damage reduction in that fashion and find it an interesting mechanic.

Verdict: I have used a Bloodman before in a Pathfinder game. The group was searching through the sewers and came upon crimson liquid floating in the sewer waters. Once it assume it's humanoid form the group was puzzled. They didn't have blunt weapons and were perplexed by his ability to deflect massive amounts of damage from their swords & arrows. It's touch attacks was hitting but it died before it could duplicate itself.
     The group was around 3rd level and having them face one was challenging for them. If the group was a bit higher I might have thrown a colony at them. Would have given more of a chance to use the duplicate ability. I highly recommend using the Bloodmen if you are want to throw something different in your group path.