Wendigo

Silent Stalker. The wendigo gets proficiency and an additional +5 to stealth rolls.

Horrid Stench. The wendigo has to re-roll any stealth checks while within 30 ft. of any creature with no proficiency and with a -3 to that roll. While in combat, all creatures within 30 ft. of the wendigo must succeed a DC 20 Constitution saving throw or be Poisoned for 1 minute. if you succeed, you are immune to the Wendigo's horrid Stench for 24 hours.

Wailing Beast. Every time the wendigo is affected by any spell or anything that would cause it to make noise, such as Tasha's Hideous Laughter, it forcibly uses Wail without expending an action.

Multiattack. The wendigo uses Claws of Necrosis twice, or uses Claws of Necrosis and Bite.

Bite. Melee Attack Roll: +14, reach 5 ft. Hit: 45 (3d12 + 27) Piercing damage, and 32(2d12 + 19).

Claws of Necrosis. Melee Attack Roll: +16, reach 10 ft. Hit: 29 (2d12 + 16) Slashing damage, and 49(3d12 + 31). The target must succeed a DC 19 Constitution saving throw or have all healing be halved for 5 rounds.

Gore. If the wendigo moves 30 ft., they can use this attack. Melee Attack Roll: +18, reach 10 ft. Hit: 72 (5d12 + 39) Bludgeoning damage and be knocked Prone.

The wendigo gets 3 legendary actions, and recharges 1d3 actions on its turn.

Frightful Presence (1/Battle). As an action, the wendigo can force each creature of its choice within 60 feet that can see or hear it to make a DC 17 Wisdom saving throw. On a failed save, creatures are frightened for 1 minute. A frightened creature can repeat the saving throw at the end of each of its turns, with disadvantage if the wendigo is within line of sight.

Move. The wendigo moves up to it's speed.

Attack. The wendigo either uses Claws of Necrosis or Bite

Wail (Recharge 5-6), (Costs 2 Actions). Ranged Spell Attack: The target everybody within 100 ft. must succeed a DC 23 Wisdom saving throw or be Frightened for 1 minute, and take 42 (3d12 + 22) Psychic damage. On a successful save, the target takes half damage and isn't Frightened, and is immune to the wail for 1 hour. Any affected creature can re-roll their save on the start of their turn, ending the effect on a success.