Basilisk Alpha

Petrifying Gaze. If a creature starts its turn within 30 feet of the basilisk and the two of them can see each other, the basilisk can force the creature to make a DC 12 Constitution saving throw if the basilisk isn't incapacitated. On a failed save, the creature magically begins to turn to stone and is restrained. It must repeat the saving throw at the end of its next turn. On a success, the effect ends. On a failure, the creature is petrified until freed by the greater restoration spell or other magic.

A creature that isn't surprised can avert its eyes to avoid the saving throw at the start of its turn. If it does so, it can't see the basilisk until the start of its next turn, when it can avert its eyes again.

If it looks at the basilisk in the meantime, it must immediately make the save. If the basilisk sees its reflection within 30 feet of it in bright light, it mistakes itself for a rival and targets itself with its gaze.

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) piercing damage plus 7 (2d6) poison damage.

Tail. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage.

The Basilisk Alpha can take 3 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 Basilisk Alpha regains spent legendary actions at the start of its turn.

Bite. The Basilisk Alpha makes a Bite attack. 

Tail. The Basilisk Alpha makes a Tail attack. 

Tail Swipe (Costs 2 Actions). The Basilisk Alpha sweeps with its large tail. Each creature within 10 feet of the dragon must succeed on a DC 16 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone.