Wendigo

Keen Hearing and Smell. The wendigo has advantage on Wisdom (Perception) checks that rely on hearing or smell.

Blood Frenzy. The wendigo has advantage on attack rolls against a creature that doesn't have all its hit points.

Regeneration. The wendigo regains 10 hit points at the start of each of its turns, provided it had a successful bite attack in the last round.  If the wendigo takes damage from a silver weapon, this trait doesn't function at the start of the wendigo's next turn.  The wendigo dies only if it starts its turn with 0 hit points and doesn't regenerate.

Legendary Resistance (2/Day). When the wendigo fails a saving throw, it can choose to succeed instead.

Multiattack. The wendigo makes two attacks: two with its shortsword (humanoid form) or one with its bite and one with its claws (hybrid form).

Bite. (Hybrid Form Only). Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 4) piercing damage. If the target is a humanoid, it must succeed on a DC 16 Constitution saving throw or be cursed with wendigo lycanthropy.

Claws. (Hybrid Form Only). Melee Weapon Attack: +9 to hit, reach 5 ft., one creature. Hit: 9 (2d4 + 4) slashing damage.

Shortsword (Humanoid Form Only). Melee or Ranged Weapon Attack: +9 to hit, reach 5 ft., one creature. Hit: 7 (1d6 + 4) piercing damage.

Change Shape. The wendigo polymorphs into a Large ghastly hybrid, or back into its true form, which appears to be a tall, thin humanoid.  Its statistics, other than its size and speed, 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.