Carnosaur

Bloody Rampage. While the carnosaur is rampaging, it has advantage on attack rolls and deals an additional  (2d10) damage on hit.

Cold Blooded. The carnosaur has advantage on saving throws against being charmed or frightened.

Frightful Presence. Each creature of the carnosaur's choice that is within 120 feet of the carnosaur and aware of it must succeed on a DC 16 Wisdom saving throw or become frightened for 1 minute. A frightened creature repeats the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the carnosaur's Frightful Presence for the next 24 hours.

Taste of Blood. If the carnosaur starts its turn grappling a creature with a carnosaur wound or hits a creature with a carnosaur wound with its bite attack, it enters a rampage that lasts 1 minute.

Primal Instinct (Recharges after a Short or Long Rest). When the carnosaur's hit points drop to 75 or fewer or it becomes charmed or frightened, it enters a rampage that lasts for one minute.

Multiattack. The carnosaur can use its Frightful Presence. It then makes three attacks: one with its bite, one with its claws, and one with its tail. It can't make its tail attack against the same target as its claw and bite attacks.

Bite. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit:  (4d12 + 8) piercing damage, or  (4d12 + 2d10 + 8) if the carnosaur is rampaging. If the target is a creature, it sustains two carnosaur wounds and is grappled (escape DC 18). Until this grapple ends, the target is restrained, and the carnosaur can't bite another target. At the end of each of the wounded creature's turns, it takes  (1d4) necrotic damage per carnosaur wound it has sustained. Carnosaur wounds can be healed if the creature regains 10 or more hit points or if a use of a healer's kit is expended on it. Alternatively, the wounded creature or another creature within 5 feet can make a DC 15 Wisdom (Medicine) check as an action, ending all carnosaur wounds on a success.

Claws. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit:  (2d8 + 8) slashing damage, or  (2d8 + 2d10 + 8) if the carnosaur is rampaging. If the target is a creature, it sustains a carnosaur wound as described in the Bite attack.

Tail. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit:  (3d8 + 8) bludgeoning damage, or  (3d8 + 2d10 + 8) if the carnosaur is rampaging.

Blood Tracking. The carnosaur learns the exact location of each creature with a carnosaur wound within 300 feet of it. It may then move up to 25 feet toward a creature wounded this way without provoking attacks of opportunity.