(I wrote this up years ago, just never posted it here)
Hit Dice: 14d8+70 (133 hp)
Speed: 60 ft. (12 squares), swim 40 ft.
Armor Class: 18 (+2 dex, +8 natural, -2 size), touch 10, flat-footed 16
Base Attack/Grapple: +10/+29
Space/Reach: 15 ft./10 ft.
Attack: Bite +22 melee (3d6+16)
Full attack: Bite +22 melee (3d6+16)
Special Attacks: Swallow whole
Special Qualities: Carrion eater, low-light vision, scent
Saves: Fort +14, Ref +11, Will +5
Abilities: Str 33, Dex 14, Con 21, Int 2, Wis 13, Cha 10
Skills: Climb +17, Listen +10, Spot +10, Survival +2*, Swim +18
Feats: Improved Natural Attack (bite), Run, Snatch, Track, Weapon Focus (bite)
Environment: Cold and temperate hills and mountains
Organization: Solitary or Mates
Challenge Rating: 10
Alignment: Always Neutral
Advancement: 15-26 HD (Huge), 27-38 HD (Gargantuan)
Level Adjustment: --
The riverbeast is one of the largest and most ferocious carnivores one is likely to ever meet. Even a dire bear looks puny side by side, and indeed riverbeasts make the occasional meal out of these ursine hulks.
They appear somewhat as giant hyenas, with compact, dog-like bodies, covered by thick fur in all shades of browns and dark tans, with striped and spotted highlights. Unlike any hyena is its meter long head with a huge, extended snout filled with teeth made for piercing and crushing. Its four legs end in four blunt hooves instead of claws which are useless for tearing. Between the front shoulder blades is a great lump of muscle giving it tremendous neck and foreleg strength.
Despite their fearsome appearance riverbeasts are mostly roaming scavengers or fishers, prowling river shores, and occasionally beaches of lakes and seas. There are rumors that riverbeasts have been seen gnawing cracked dragon turtles shells with ease.
Riverbeasts are around 18 feet long from snout to tail and weigh about 12,000 lbs.
Riverbeasts are fearsome fighters, using their immense jaw muscles to crush out of shape whatever it get a hold of. If carrion is not readily available they do not hesitate to leap upon anything of sufficient size to satisfy their hunger, snatching it up in their awesome jaws and snapping bones and shell which it eats as readily as the meat. Any creatures of smaller than Medium size are generally beneath its notice. They enjoy the water and will pursue aquatic prey as well as those that are land bound.
Carrion Eater (Ex):
As a result of the riverbeast's proclivity for carrion it gains a +4 bonus to fortitude saves against disease.
Swallow Whole (Ex):
A riverbeast can try to swallow a grabbed opponent of up to two sizes smaller by making a successful grapple check. The swallowed creature takes 2d6+8 points of bludgeoning damage and 8 points of acid damage per round from the riverbeast's gizzard. A swallowed creature can cut its way out by using a light slashing or piercing weapon to deal 20 points of damage to the gizzard (AC 12). Once the creature exits, muscular action closes the hole; another swallowed opponent must cut its own way out.
A riverbeast's gizard can hold 1 Medium, 2 Small, 8 Tiny, or 32 Diminutive or small opponents.
: A riverbeast has a +4 racial bonus on Listen and Spot checks, and a +6 bonus on climb and swim checks.
*It also gains a +6 racial bonus on Survival checks when tracking by scent.