Cragwater Behemoth

Spider Climb. The Behemoth can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Pounce. If the Behemoth moves at least 20 feet straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 16 Strength saving throw or be knocked prone. If the target is prone, the Behemoth can make one bite attack against it as a bonus action.

Hold Breath. The Behemoth can hold its breath for 30 minutes.

Cragwater Camouflage.  The Behemoth has advantage on Dexterity (Stealth) checks made to hide underwater in rocky terrain.

Multiattack. The Behemoth makes two attacks: one with its bite and one with its tail or claw.

Bite. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 34 (4d12 + 6) piercing damage, and the target is grappled (escape DC 16). Until this grapple ends, the target is restrained, and the Behemoth can't bite another target.

Claw. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 30 (4d10 + 6) slashing damage. 

Tail. Melee Weapon Attack: +11 to hit, reach 10 ft., one target not grappled by the Behemoth. Hit: 26 (4d8 + 6) bludgeoning damage. If the target is a creature, it must succeed on a DC 16 Strength saving throw or be knocked prone.