Flyby. The cockatrice doesn't provoke an Opportunity Attack when it flies out of an enemy's reach.
Multiattack. The cockatrice makes one Petrifying Bite attack and two Talons attacks.
Petrifying Bite. Melee Attack Roll: +7, reach 5 ft. Hit:13 (2d8 + 4) Piercing damage. If the target is a creature, it is subjected to the following effect. Constitution Saving Throw: DC 14. First Failure: The target has the Restrained condition and repeats the save at the end of its next turn if it is still Restrained, ending the effect on itself on a success. Second Failure: The target has the Petrified condition instead of the Restrained condition.
Talons. Melee Attack Roll: +7, reach 5 ft. Hit:18 (4d6 + 4) Slashing damage.
Magical Backlash. Trigger: A creature within 120 feet of the cockatrice deals damage to it. Response—Dexterity Saving Throw: DC 14, the triggering creature. Failure: 13 (3d6 + 3) Force damage.
Accursed Avians with the Power to Petrify