Avian Hydra

Hold Breath. The hydra can hold its breath for 30 minutes.

Multiple Heads. The hydra has six 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 avian hydra takes 30 or more damage in a single turn, one of its heads dies. If all its heads die, the hydra dies.

At the end of its turn, it grows two heads for each of its heads that died since its last turn, unless it has taken damage from a melee weapon attack since its last turn. The hydra regains 10 hit points for each head regrown in this way.

Reactive Heads. For each head the hydra has beyond one, it gets an extra reaction that can be used only for opportunity attacks.

Multiattack. The avian hydra makes as many honk attacks as it has heads.

Honk. Ranged Weapon Attack: +8 to hit, range 10/20 ft., all non-avian hydra targets in range. Hit: 10 (1d6 + 3) piercing damage + (1d4 + 2) psychic damage.

Eldritch Honks. The avian hydra utilizes all of it's alive heads to create a cacophony of sound, magnifying the volume and intensity. All other creatures within 40 ft. must make a DC 18 Constitution saving throw, taking 6d10+10 psychic damage on failed save, and only taking half that damage on a successful one. Creatures who failed the throw are additionally deafened and frightened for 2 turns.
The avian hydra foregoes it's multiattack this turn; Eldritch Honks cannot be used on the subsequent turn.