Huge Construct
-------------------------------------------------------------------------
Hit Dice: 30d10 (155 hp)
Initiative: +11 (Dex)
Speed: 40 ft., swim 15 ft.
AC: 37 (–2 size, +11 Dex, +18 natural)
Attacks: 2 Slams +24 melee
Damage: Slam 2d10 + 8
Face/Reach: 10 ft. by 10 ft./15 ft.
Special Attacks: Blood drain, improved grab
Special Qualities: Construct, magic immunity, damage reduction 50/+3
Saves: Fort —, Ref +21, Will +10
Abilities: Str 18, Dex 32, Con —, Int —, Wis 10, Cha 1
-------------------------------------------------------------------------
Climate/Terrain: Any land
Organization: Solitary or gang (2-4)
Challenge Rating: 18
Treasure: None
Alignment: Always neutral
Advancement: 31-38 HD (Huge); 39-52 HD (Gargantuan)
-------------------------------------------------------------------------
Where most golems are the creation of great wizards, forcing the spirits of elemental earth to take up residency in unyeilding forms, the blood golem is of a different sort - and innovative mage, tired of earth, attempted to create a giant flesh golem, using a trapped water elemental. The experiment was a failure, but it yielded the information necessary for the creation of the blood golem.
The blood golem is a giant monstrosity, a humanoid shape, towering some fifteen feet, their twisted shapes a mockery of life, dripping blood that never seems to run out. The creature moves with a fluid grace, swiftness and size belying it's enormous bulk.
Combat
Blood golems are awesome combatants, rivaling the legendary iron golems in combat - though, as their advocates say, the blood golem could give even an iron golem pause. Lashing out with tendrils of blood, they latch onto their targets and begin to drain their life, swelling as they do.
Blood Drain (Su): Once a target is successfully held, the blood golem begins to drain 1d4 points of Constitution per round. For each point of Constitution drained, the blood golem gains one effective hit die, gaining 8 hit points, and +1 to attack and damage.
Improved Grab (Ex): To use this ability, the blood golem must hit with both slam attacks. If it does, it may attempt to grapple (hold) it's foe immediately.
Construct: Immune to mind-influencing effects, poison, disease, and similar effects. Not subject to critical hits, subdual damage, ability damage, energy drain, or death from massive damage.
Magic Immunity (Ex): Blood golems are immune to all spell, spell-like abilities, and supernatural effects, except as follows. Any cold spell slows it as per the spell, but inflicts no damage. Contact with electricity immediately dispels the slow effect, and cures one point of damage for every three the spell would have inflicted. A horrid wilting kills the blood golem immediately.
Ok, that'd be my best guess at the thing. I'd imagine a blood golem would be quick and dextrous, as opposed to lumbering and being able to smash things into a pulp. 
