Werecrocodile

Shapechanger. The werecrocodile can use its action to polymorph into a Large crocodile-humanoid hybrid or into a Large crocodile, or back into its true form, which is humanoid. Its statistics, other than its size and AC, are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Keen Senses. The werecrocodile has advantage on Wisdom (Perception) checks that rely on smell, sight, and sound.

Darkvision. The werecrocodile can see in dim light within 60 feet of it as if it were bright light, and in darkness as if it were dim light.

Amphibious. The werecrocodile can breathe air or water.

Lying in Wait. If the werecrocodile is submerged in water, it cannot be detected by anything that does not succeed on a DC 19 Perception check. Its passive perception becomes 20 in this state.

Watersense. The werecrocodile can see as if it had tremorsense up to 30 feet so long as it is in a body of liquid. It cannot use this to detect creatures outside of the same body of liquid.

Ambush Predator. If the werecrocodile is submerged in a body of liquid and making an attack of opportunity against a target, it may add its Stealth modifier to the attack and damage rolls.

Burst of Speed. If the werecrocodile has moved as much as it can in a turn and has not attacked, but there is an enemy within 10 feet of it, it may move an additional 10 feet to become adjacent to that enemy.

Multiattack. In crocodile form, the werecrocodile makes two bite attacks. In humanoid form, it makes two attacks with whatever weapon it might possess. In hybrid form, it can attack like a crocodile or a humanoid.

Bite (Crocodile or Hybrid Form Only). Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 15 (2d10 + 5) piercing damage. If the target is a humanoid, it must succeed on a DC 14 Constitution saving throw or be cursed with werecrocodile lycanthropy. The target must succeed on a DC 19 Strength saving throw or become grappled if they are of medium size or smaller.

Tail (Crocodile or Hybrid Form Only). Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 5) bludgeoning damage. If the target is a humanoid, it must succeed on a DC 14 Constitution saving throw or be knocked prone.

Deathroll (Crocodile or Hybrid Form Only).  If the werecrocodile has a target grappled via its bite attack, it may use this attack once per combat. The target then makes a DC 20 Strength saving throw. The target takes 4d8 bludgeoning damage on a failed save or half as much on a successful save. If the target succeeds, they are no longer grappled.