Calamity Gorgon

Trampling Charge. If the gorgon moves at least 20 feet straight toward a creature and then hits it with a gore attack on the same turn, that target must succeed on a DC 16 Strength saving throw or be knocked prone. If the target is prone, the gorgon can make one attack with its hooves against it as a bonus action.

Poisonous Blood. Any creature within 5 feet of the Gorgon takes 1d12 Poison damage each time it is struck with a nonmagical attack that deals Bludgeoning, Piercing or Slashing damage

Gore. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 18 (2d12 + 5) piercing damage.

Hooves. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 16 (2d10 + 5) bludgeoning damage.

Petrifying Breath (Recharge 5–6). The gorgon exhales petrifying gas in a 30-foot cone. Each creature in that area must succeed on a DC 13 Constitution saving throw. On a failed save, a target begins to turn to stone and is restrained. The restrained target must repeat the saving throw at the end of its next turn. On a success, the effect ends on the target. On a failure, the target is petrified until freed by the greater restoration spell or other magic.

A remnant of the Calamity and affected by the wild magics of the Blightshore, the Gorgon can use 3 Legendary actions in a round. 

Defensive Shift -  The Gorgon can move 20 in any direction and does not provoke Opportunity Attacks when doing so (Cost: 1 Legendary Action)

Attack - The Gorgon can make 1 Attack (Cost: 1 Legendary Action)

Tighten Armor - The Gorgon can shift its metal plates, drawing them closer together and increasing its AC by +4 for 1 round (Cost: 2 Legendary Actions)

Legendary Resistance - 3