Crimson Shark

Blood Frenzy: The Crimson Shark has advantage on attack rolls made agaisnt cretaures with half of their maximum hit points.

Red Mist Native: The Crimson Shark can use its swiming speed in the Red Blood Mist terrain and can see normaly within that terrain.

Multiattack: The Crimson Shark can make one Jaws and one Tail attack on its attack action.

Jaws: Melee Weapon Attack +9 to hit, 5ft reach, one target, for 3d8+6 piercing damage, the Crimson Shark regains hit points equal to half of the damage dealt.

Furthermore creatures of large or smaller size must succeed in a DC 17 Strength saving throw being restrained within the Crimson Shark´s Jaws on a failure.

A creature restrained in this way can at the start of its following turns atempt to escape by succeeding in a DC 17 Strength saving throw.

Tail: Melee Weapon Attack +9 to hit 10ft reach, one target, for 3d12+6 bludgeoning damage.

Crunch: The Crimson Shark closes its jaws with power, a creature restrain within its Jaws takes 3d8 piercing damage. 

The Crimson Shark regains hit points equal to half of the damage dealt.