Big Bad Wolf

Keen Senses. The wolf has advantage on Wisdom (Perception) checks relying on smell.

Magic Resistance. The fey  has advantage on saving throws against spells and other magical effects.

Fey Presence. The Fey  can chose to force any creatures within 10 feet of it to make a DC 16 Wisdom saving throw. On a failure, a creature is charmed by the fey for 1 hour or until she ends the effect, the creature moves 60 ft away from her, or is freed by other means. On a success, a creature is immune to her Presence for 24 hours.

Siege Monster. The wolf deals double damage to structures.

Multiattack. The wolf makes 2 bite attacks. It may substitute one of these attacks with its swallow action

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 11 (1d10 + 6) piercing damage and the creature must succeed on a DC 17 Strength saving throw or be knocked prone.

Swallow. The wolf swallows one prone Medium or Small creature. The swallowed creature is blinded, restrained, and has total cover from attacks and effects outside the wolf. A swallowed creature takes 5 (2d4) acid damage at the start of each of the wolf's turns. If the wolf takes 10 damage from a swallowed creature, the wolf must succeed on a DC 20 Constitution saving throw or regurgitate all swallowed creatures. Regurgitated creatures exit prone, in an unoccupied space within 10 ft of the wolf. The wolf can have two creatures swallowed at a time.

Huff and Puff (Recharge 5–6).  The wolf exhales repulsion energy in a 30-foot cone. Each creature in the area of effect must make a DC 15 Dexterity saving throw, taking 27 (5d10) force damage and be pushed 40 feet away from the wolf, landing prone, on a failed save, or half as much damage on a successful one and is not pushed.

The wolf has 3 legendary actions. It can use one of the actions below at the end of another creature’s turns, and regains all uses at the end of its turn.

Detect. The wolf makes a perception check.

Bound. The wolf moves up to its speed without triggering opportunity attacks.

Swallow. The wolf uses its swallow action against a prone target