Basilisk King

Petrifying Gazes. If a creature starts its turn within 30 feet of the basilisk king and the two of them can see each other, the basilisk king can force the creature to make a DC 15 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 king in the meantime, it must immediately make the save. If the basilisk king sees a reflection of one of the other heads within 30 feet of it in bright light, it mistakes it for a rival and targets it with its gaze.

Multiple Heads. The basilisk king has three heads. While it has more than one head, the hydra has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Whenever the Basilisk King takes 50 or more damage in a single turn, one of its heads dies. If all its heads die, the Basilisk King dies.

The basilisk king makes as many bite attacks as it has heads.

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) piercing damage plus 7 (2d6) poison damage.

Roar. The Basilisk King releases a series of roars from its mouths. Creatures within 30 feet of the Basilisk King must make a DC 15 Wisdom saving throw or be stunned for one minute. They can make the saving throw again at the end of each of their turns.