Brood Keeper (CR 16)

Huge Magical Beast
Alignment: Usually neutral
Initiative: +3 (Dex); Senses: darkvision 60 ft., low-light vision, Listen +14, and Spot +14

AC: 25 (-2 size, +3 Dex, +14 natural), touch 11, flat-footed 22
Hit Dice: 22d10+154 (275 hp); DR: 5/-
Fort +22, Ref +18, Will +12
Speed: 60 ft.
Space: 15 ft./10 ft.
Base Attack +22; Grapple +37
Attack: Claw +27 melee
Full Attack: 2 claws +27 melee and bite +25 melee
Damage: Claw 1d8+7, Bite 2d6+3 plus poison
Special Attacks/Actions: Fear, improved grab, larva swarm, pounce, rake, rend 2d8+10
Abilities: Str 25, Dex 17, Con 25, Int 6, Wis 16, Cha 8
Special Qualities: evasion, fast healing 5, SR 26
Feats: Alertness; Dodge; Great Fortitude; Iron Will; Lightning Reflexes; Mobility; Multiattack; Run
Skills: Jump +26 (+30 running jump), Listen +14, and Spot +14
Advancement: 23-31 HD (Huge); 32-44 HD (Gargantuan)
Climate/Terrain: Warm plains
Organization: Solitary
Treasure/Possessions: None

Source: Monster Manual III

Fear (Su): A creature that witnesses a brood keeper rend a foe or release its larva swarm must make a DC 20 Will save or be frightened for 1d10 rounds and shaken for 1 hour. Creatures that succeed on the save are shaken for 1d4 rounds and immune to that brood keeper's fear effect for 24 hours. This is a mind-affecting fear effect. The save DC is Charisma-based.

Improved Grab (Ex): To use this ability, a brood keeper must hit with its bite attack. It can then attempt to start a grapple as a free action without provoking attacks of opportunity. If it wins the grapple check, it establishes a hold.

Larva Swarm (Ex): As a full-round action, a brood keeper can lift the plates of chitin on its back, releasing a brood keeper larva swarm. The brood keeper larva swarm can act immediately. Until its next action, the brood keeper takes a -5 penalty to Armor Class. Brood keepers are immune to a brood keeper larva swarm's distraction and swarm attacks. A brood keeper can call its larva swarm back as a free action, but it is a full-round action to accept them back into its carapace, during which time the brood keeper takes a -5 penalty to Armor Class. Releasing or accepting its larva swarm provokes attacks of opportunity.

A brood keeper can keep only one brood of larvae in its back. Should the larva swarm be damaged so much that it disperses, a brood keeper gives birth to another batch of larvae in 1 month. If the brood keeper has not done so already, it automatically releases its brood of larvae when it dies.

Pounce (Ex): When a brood keeper charges, it can make a full attack, including four rake attacks.

Rake (Ex): Attack bonus +25 melee, damage 1d8+3. A brood keeper rakes with all four back legs, granting it four extra claw attacks when it begins a round in a grapple or when it pounces.

Rend (Ex): If a brood keeper hits with at a bite or claw attack and at least one rake attack, it rips its foe apart. This attack automatically deals 2d8+10 points of damage.

Evasion (Ex): If the brood keeper makes a successful Reflex saving throw against an attack that normally deals half damage on a successful save, it instead takes no damage.

A brood keeper charges and pounces on one foe, then claws at another. It attacks each enemy it can reach with a charge in turn and releases its larva swarm to attack prey that is farther away.