Bewilderbeast

Amphibious. The Bewilderbeast can breathe air and water.

Multiattack. The Bewilderbeast makes two Bite attacks and one Tusk attack

Bite. Melee Weapon Attack: +12 to hit, reach 5 ft., 1 target. Hit: 24 (4d6 + 4) piercing damage plus 12 (4d4 + 4) cold damage.

Tusk. Melee Weapon Attack: +5 to hit, reach 40 ft., 1 target. Hit: 30 (7d4 + 5)

Ice Breath. The Bewilderbeast exhales a 100 ft cone of ice. Eeach creature in that cone takes 5d12 cold damage and take a DC 30 Dexterity saving throw or be knocked prone by the ice.

Frightful Presence. Each creature that can see the Bewilderbeast must make a DC 17 Wisdom saving throw or be frightened by the Bewilderbeast until the end of the Bewilderbeast's next turn

The Bewilderbeast can take 2 legendary actions choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The Bewilderbeast regains spent legendary actions at the start of its turn.

Mind Bend (Costs 3 Actions). Every Dragon within 150 feet of the Bewilderbeast must make a DC 30 Wisdom saving throw or be charmed by the Bewilderbeast and must follow its commands until the end of its next turn.

Sonic Roar (Costs 2 Actions). The Bewilderbeast roars. Every creature within 50 feet of the Bewilderbeast must make a DC 15 Wisdom saving throw and take 2d20 thunder damage on a failed save, or half as much damage on a successful one.