Mastodon, Grizzly (CR 13)

Huge Animal
Alignment: Always neutral
Initiative: +0; Senses: darkvision 60 ft., low-light vision, scent, Listen +11, and Spot +11

AC: 16 (-2 size, +8 natural), touch 8, flat-footed 16
Hit Dice: 15d8+96 (163 hp)
Fort +15, Ref +9, Will +7
Speed: 40 ft.
Space: 15 ft./10 ft.
Base Attack +11; Grapple +31
Attack: Slam +21 melee and 2 stamps +16 melee, or gore +21 melee
Full Attack: Slam +21 melee and 2 stamps +16 melee, or gore +21 melee
Damage: Slam 2d6+12, stamp 2d6+6, gore 4d8+12
Special Attacks/Actions: Trample 4d8+18
Abilities: Str 35, Dex 10, Con 23, Int 2, Wis 15, Cha 7
Special Qualities:
Feats: Alertness; Endurance; Improved Bull Rush; Power Attack; Toughness x2
Skills: Listen +11 and Spot +11
Advancement: 16-21 HD (Huge); 22-45 HD (Gargantuan)
Climate/Terrain: Cold and temperate hills and forests
Organization: Solitary or herd (6-30)
Treasure/Possessions: None

Source: Monster Manual II

Trample (Ex): As a standard action, a grizzly mastodon can trample opponents at least one size category smaller than itself. This attack deals 4d8+18 points of bludgeoning damage. A trampled opponent can attempt either an attack of opportunity at a -4 penalty or a Reflex save (DC 29) for half damage.

Scent (Ex): A grizzly mastodon can detect approaching enemies, sniff out hidden foes, and track by sense of smell.

In combat, grizzly mastodons gore with their four tusks, then trample opponents underfoot. They prefer to attack in groups, but they show no fear even when overmatched if the safety of their young is at stake.