Airavat

Acidic Blood. When the hydra takes piercing or slashing damage, each creature within 5 feet of the hydra takes 9 (2d8) acid damage.

Hold Breath. The hydra can hold its breath for 1 hour.

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

Whenever the hydra takes 35 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 fire damage 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.

Wakeful. While the hydra sleeps, at least one of its heads is awake.

Grappler. Airavat has advantage on attack rolls against any creature grappled by him.

Multiattack. Airavat makes as many trunk attacks as he has heads, each of which he can replace with a grapple or one use of Fling.

Trunk. Melee Weapon Attack: +10 to hit, reach 15 ft., one creature. Hit: 17 (2d10 + 6) bludgeoning damage.

Fling. One Large or smaller object held or creature grappled by Airavat is thrown up to 100 feet in any direction. If the thrown target strikes a solid surface, the target takes 5 (1d10) damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 15 Dexterity saving throw or take the same damage and be knocked prone.