I got around to statting a rabbit and a modified Brobdingnagian Teratoid rabbit:
EASTERN COTTONTAIL RABBIT (SYLVILAGUS FLORIDANUS)
Tiny Animal
Hit Dice: ½d8 (2 hp)
Initiative: +4
Speed: 60 ft. (3 squares), burrow 5 ft. (soil)
Armor Class: 16 (+2 size, +4 Dex), touch 16, flat-footed 12,
Base Attack/Grapple: +0/-12
Attack: Bite +6 melee (1d3-4)
Full Attack: Bite +6 melee (1d3-4)
Space/Reach: 2½ ft./0 ft.
Special Attacks: —
Special Qualities: Low-light vision, scent
Saves: Fort +2, Ref +6, Will +1
Abilities: Str 3, Dex 18, Con 11, Int 2, Wis 12, Cha 7
Skills: Jump +12 (+4 skill ranks, -4 Strength, +12 movement speed)
Feats: Run, Weapon Finesse^B
Environment: Temperate plains and forests
Organization: Domesticated or warren (5-30)
Challenge Rating: ⅙
Treasure: None
Alignment: Always neutral
Advancement: —
Level Adjustment: —
Eastern Cottontail rabbits have long ears and a short, fluffy tall. Their hind legs are longer than their front legs with hind feet that are significantly larger than the front feet. The upper body is usually reddish brown with the underparts white, including the underside of the tall. There is a rusty colored patch on the nape of the neck and often a white spot on the forehead. Eastern Cottontails usually weigh from 2 to 4 pounds and have a total length of 12 to almost 20 inches.
Skills: A rabbit can always take 10 on Jump checks, even under stress. In addition, it receives a +12 bonus to Jump checks due to its 60 ft. movement speed.
BROBDINGNAGIAN BEHEMOTH RABBIT
Colossal Animal
Hit Dice: 49d8+441 (661 hp)
Initiative: +0
Speed: 480 ft. (96 squares), burrow 40 ft. (soil)
Armor Class: 28 (-8 size, +26 natural), touch 2, flat-footed 28
Base Attack/Grapple: +36/+72
Attack: Bite +52 melee (4d8+38/19-20 + 1d6 and DC 54 save-or-die on a critical hit)
Full Attack: Bite +52 melee (4d8+38/19-20 + 1d6 and DC 54 save-or-die on a critical hit)
Space/Reach: 60 ft./85 ft. (30 ft./20 ft. if using WotC's core space/reach rules)
Special Attacks: Earthshaker, improved grab, swallow whole, trample
Special Qualities: Low-light vision, scent
Saves: Fort +35, Ref +26, Will +17
Abilities: Str 51, Dex 10, Con 29, Int 2, Wis 12, Cha 7
Skills: Jump +252 (+52 skill ranks, +20 Strength, +180 movement speed)
Feats: Awesome Blow, Cleave, Devastating Critical (Bite), Epic Weapon Focus (Bite), Epic Weapon Specialization (Bite), Great Cleave, Greater Weapon Focus (Bite), Greater Weapon Specialization (Bite), Improved Critical (Bite), Improved Natural Attack (Bite), Improved Overrun, Overwhelming Critical (Bite), Power Attack, Run, Snatch, Weapon Focus (Bite), Weapon Specialization (Bite)
Environment: Temperate plains and forests
Organization: Domesticated or warren (5-30)
Challenge Rating: 21
Treasure: None
Alignment: Always neutral
Advancement: —
Level Adjustment: —
A brobdingnagian behemoth rabbit is a cottontail with all of its dimensions increased by a factor of 64 and its mass increased by a factor of 262,144. As such, a brobdingnagian behemoth rabbit has a total length of 64 to almost 107 feet and an average weight of 262 (43 HD) to 524 tons (53 HD). The example given in the statistics above is an average specimen with a length of 86 feet and a mass of 393 tons and as such has 49 HD. Certain smaller and larger rabbits of such kind are known to exist.
Earthshaker (Ex): A brobdingnagian behemoth rabbit’s great leaps rend the ground through sheer impact. Whenever it takes a move action or tramples, a brobdingnagian behemoth rabbit causes an Earthquake in an 80-foot spread centered on the rabbit as the spell of the same name. Only one Earthquake may be caused per round, and the rabbit must select the point at which it starts the earthquake during its movement.
Improved Grab (Ex): To use this ability, a brobdingnagian behemoth rabbit must hit a Medium or smaller opponent with its bite attack. It can then attempt to start a grapple as a free action without provoking an attack of opportunity. If it wins the grapple check, it establishes a hold and can try to swallow the foe the following round.
Swallow Whole (Ex): A brobdingnagian behemoth rabbit can try to swallow a grabbed opponent of Medium or smaller size by making a successful grapple check. Once inside, the opponent takes 2d8+9 points of crushing damage plus 2d8+4 points of acid damage per round from the rabbit’s digestive juices. A swallowed creature can cut its way out by dealing 58 points of damage to the rabbit’s digestive tract (AC 23). Once the creature exits, muscular action closes the hole; another swallowed opponent must cut its own way out. The rabbit’s gullet can hold 2 Medium, 8 Small, 32 Tiny, 128 Diminutive, or 512 Fine or smaller creatures.
Trample (Ex): 4d6+30 damage, Reflex DC 54 half. The save DC is Strength-based.
Skills: A brobdingnagian behemoth rabbit can, always take 10 on Jump checks even under stress. In addition, it receives a +180 bonus to Jump checks due to its 480 ft. movement speed.
BROBDINGNAGIAN BEHEMOTH RABBIT (CR Analysis using v5)
Hit Dice: 49 Animal HD ... ECL +26.95
Type: Animal ... ECL -0.75
Improved Natural Attack (already included in full attack) ... ECL -0.2
Ability Scores: 111 (48 points over 63) ... ECL +4.8
Size: Colossal ... ECL +1
Speed: 480 ft. (6 doublings from 15 ft.) ... ECL +1.2
Speed: Burrow 40 ft. (Soil) ... ECL +0.2
Full Attack: 18 average dice damage ... ECL +1.8
Special Attack: Improved Grab ... ECL +0.2
Special Attack: Swallow Whole (18 average damage dice) ... ECL +0.9
Special Attack: Trample (14 average damage dice) ... ECL +0.7
Special Quality: Scent ... ECL +0.2
Spell-like Ability: Quickened Earthquake (CL 23) At Will ... ECL +1.38
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Total ECL Factor = ECL 38.38
Golden Rule = ECL 38.38
Silver Rule = ECL 32.623
Challenge Rating = CR 21.748667
Final Challenge Rating = CR 21
EDIT: Fixed the bite damage.
