And I bring you Hobb's Leviathan (a.k.a. Gigantoserpen). Am I the only one cheesed off that I am updating at a rate of once per week? Its annoying the heck out of me.

Anyway, I am sort of unsatisfied with the CR on this one. It seems that VP's CR calculator begins to fall apart once the sack of hp is too big. Ah well. Using the calculator, this thing comes up as CR 34; an obvious impossibility, if only because having this thing attack epic PCs is like feeding it to a whale-sized meat grinder. I dropped it to CR 21, and made the abilities pretty nasty. More play testing is neccesary to get an actual CR, though...

Gigantoserpen
Colossal Animal (Aquatic)
Hit Dice: 34d8+442 (595 hp)
Initiative: +2
Speed: Swim 40 ft. (8 squares)
Armor Class: 34 (-8 size, +30 natural, +2 Dex), touch 4, flatfooted 32
Base Attack/Grapple: +25/+48
Attack: Bite +25 melee (4d6+13/19-20)
Full Attack: Bite +25 melee (4d6+13/19-20), and 2 Slams +19 melee (3d6+7)
Space/Reach: 30 ft./20 ft.
Special Attacks: Improved Grab, Swallow Whole, infected bite
Special Qualities: Lowlight vision, keen scent, feces expulsion
Saves: Fort +34, Ref +23, Will +13
Abilities: Str 25, Dex 14, Con 37, Int 2, Wis 11, Cha 8
Skills: Listen +39, Spot +2, Swim +15
Feats: Alertness, Great Fortitude, Improved Scent, Improved Critical (Bite), Iron Will, Lightning Reflexes, Overpowering Stench, Rancid Smell, Uncanny Scent Weapon Focus (Bite)
Epic Feats: Epic Scent
Environment: Warm Aquatic
Organization: Solitary
Challenge Rating: 21
Treasure: None
Advancement: 34+ (Colossal)
Level Adjustment: -----

In the dark water below, a massive shape slowly moves forward. It is almost like a giant, submerged island. At the far end of the great shadow, a small head rises out from the water.

Gigantoserpen are descendants of mosasaurs who, have thrived for millions of years. At one point, it is believed that all sorts of different mosasaur species swam in the world’s waters, but eventually dwindled to the point that only a few types were left. Before this time, though, a new species evolved, one that was so large that it had no natural predators. These creatures are known as Gigantoserpen.

These creatures are nearly 70 ft. in length, and may weigh as much as 66 tons (nearly the same weight as 30 elephants!). Because of their lack of rivals, these creatures have a much more passive approach to hunting and killing then their kin. For the most part, they consume vast quantities of fish and other 3 ft. long prey. They have been known to swallow the occasional Halfling swimmer, though. When given the chance, they may also try larger prey, like humans and small giants.

Gigantoserpen appears to be a massive lizard that looks similar to early plesiosaurs. This is an illusion, though. The fact that its fore body is several times smaller gives it a seemingly long neck. In reality, its tiny front limbs are close to its head, while its aft body is several times larger. This also gives it a fish-like appearance, though it is definitely reptilian. One of its more distinguishing features is an odd organ found by the lower intestines. Instead of excreting wastes like most creatures, it gathers up and stores a large amount. When frightened or in need of a quick escape (which is, unsurprisingly, not often), it releases the feces in a massive, sickening brown cloud.

Combat
Gigantoserpen do not worry much about combat, as its massive bulk deters most prey. Their primary attack, a nasty bite, is very painful, though, and more than capable of killing a human. It is also known for occasionally “slapping” its prey, thrusting its large flippers against smaller prey in an attempt to push them away. The resulting slam can be quite painful.

Feces Expulsion (Ex): Once per week, as an immediate action, the Gigantoserpen may release a literal ton of wastes into the waters surrounding it. This creates a 90 ft. radius of brown, diseased water. All creatures within this radius are blinded, and must make a DC 30 fortitude save, or be nauseated for 3d10 rounds. Even afterwards, the creatures are sickened for an additional 3d10 rounds.

Improved Grab (Ex): Each time the Gigantoserpen successfully bites an opponent, it may initiate a grapple as a free action without provoking an attack of opportunity.

Keen Scent (Ex): A Gigantoserpen can notice creatures in the water at a ranged of 180 ft., and can pinpoint the location of creatures within 30 ft. of it.

Swallow Whole (Ex): If a Gigantoserpen begins its turn with an opponent held in its mouth, it can attempt a new grapple check (as though attempting to pin the opponent). If it succeeds, it swallows its prey, and the opponent takes bite damage. This deals 6d6+14 bludgeoning damage, and 18 points of acid damage each round the swallowed creature remains in the stomach. A swallowed creature is considered to be grappled, while the creature that did the swallowing is not. A swallowed creature can try to cut its way free with any light slashing or piercing weapon by causing 75 points of damage, or it can just try to escape the grapple. The Armor Class of the interior of the Gigantoserpen is 25. If the swallowed creature escapes the grapple, success puts it back in the attacker’s mouth, where it may be bitten or swallowed again.