Anatis

Three heads. the Anatis has advantage on saving throws against being blinded, deafened, petrified, paralyzed, stunned, or knocked unconscious.

Wakeful. when the Anatis is asleep, at least one of it's heads is awake.

Brave. the Anatis has advantage on saving throws against being frightened.

Regeneration. the Anatis regains 10 hit points at the start of it's turn if it has at least one hit point. this trait doesn't function if it has taken necrotic damage since the start of it's last turn.

Multiattack. the Anatis makes three bite attacks. or one wing attack.

Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., 1 target. Hit: 25 (4d8 + 9) bludgeoning damage. 

Wing Attack. Melee Weapon Attack: +9 to hit, All targets within a 10 foot high, 20 foot radius cylinder centered on the Anatis. Hit: 60 (7d10 + 25) bludgeoning damage. and each target must make a DC 17 strength saving throw or be knocked prone. then, the Anatis may move up to half it's flying speed.