Crocosphinx (CR 12)

Large Magical Beast
Alignment: Always chaotic evil
Initiative: -1 (Dex); Senses: darkvision 60 ft., low-light vision, Listen +22, and Spot +22

AC: 23 (-1 size, -1 Dex, +15 natural), touch 8, flat-footed 23
Hit Dice: 15d10+90 (172 hp)
Fort +15, Ref +8, Will +7
Speed: 40 ft., fly 60 ft. (poor), swim 40 ft.
Space: 10 ft./5 ft.
Base Attack +15; Grapple +27
Attack: Bite +22 melee or tail slap +22 melee
Full Attack: Bite +22 melee and 2 claws +17 melee; or tail slap +22 melee and 2 claws +17 melee
Damage: Bite 2d6+8, claws 2d4+4, tail slap 1d12+12
Special Attacks/Actions: Improved grab, pounce, rake 2d4+4
Abilities: Str 26, Dex 8, Con 23, Int 13, Wis 14, Cha 15
Special Qualities: hold breath
Feats: Alertness; Awesome Blow; Cleave; Flyby Attack; Improved Bull Rush; Power Attack
Skills: Hide +8*, Intimidate +11, Listen +22, Spot +22, and Swim +8
Advancement: 16-22 HD (Large); 23-45 HD (Huge)
Climate/Terrain: Warm deserts
Organization: Solitary
Treasure/Possessions: Standard

Source: Sandstorm

Hold Breath (Ex): A crocosphinx can hold its breath for a number of rounds equal to 4 x its Constitution score before it risks drowning.

Improved Grab (Ex): To use this ability, a sphinx must hit a creature 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, the crocosphinx establishes a hold on the opponent and drags it into deep water, attempting to pin it to the bottom.

Pounce (Ex): If a sphinx charges a foe, it can make a full attack, including two rake attacks.

Rake (Ex): A sphinx that pounces onto a creature can make two rake attacks with its hind legs. Attack bonus +17, damage 2d4+4.

Skills (Ex): A crocosphinx has a +8 racial bonus on any Swim check to perform some special action to avoid a hazard. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line. *A crocosphinx gains a +4 racial bonus on Hide checks when in the water. Further, a crocosphinx can lie in the water with only its eyes and nostrils showing, gaining a +10 circumstance bonus on Hide checks.

A crocosphinxes pounces on its opponent from beneath the water, then drags it in and attempts to drown the victim.