Toad, Titanic* (CR 13)

Gargantuan Animal
Alignment: Always Neutral
Initiative: +0; Senses: low-light vision, Listen +13, and Spot +13

AC: 26 (-4 size, +20 natural), touch 6, flat-footed 26
Hit Dice: 25d8+203 (315 hp)
Fort +24, Ref +14, Will +16
Speed: 20 ft.
Space: 20 ft./15 ft.
Base Attack +18; Grapple +26
Attack: Bite +27 melee
Full Attack: Bite +27 melee
Damage: Bite 3d8+19
Special Attacks/Actions: Trample 3d8+19
Abilities: Str 37, Dex 10, Con 27, Int 1, Wis 14, Cha 4
Special Qualities:
Feats: Favored: Awesome Blow; Great Fortitude; Improved Bull Rush; Power Attack; Toughness
Skills: Hide +2, Listen +13, and Spot +13
Advancement: -
Climate/Terrain: Temperate and warm land and aquatic
Organization: Solitary
Treasure/Possessions: None

Source: Monster Manual II

Trample (Ex): As a standard action during its turn each round, a titanic toad can trample a Huge or smaller opponent. This attack deals 3d8+19 points of bludgeoning damage. A trampled opponent can attempt either an attack of opportunity at a -4 penalty or a Reflex save (DC 35) for half damage.