Aku'Tal

Aku'Tal can hold its breath for 1 hour.

Aku'Tal has five heads. While it has more than one head, Aku'Tal has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Whenever Aku'Tal takes 25 or more damage in a single turn, one of its heads dies. If all its heads die, Aku'Tal 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. Aku'Tal regains 10 hit points for each head regrown in this way.

For each head Aku'Tal has beyond one, it gets an extra reaction that can be used only for opportunity attacks.

While Aku'Tal sleeps, at least one of its heads is awake.

Each head functions independently, rolling its own initiative and capable of moving up to 10 feet in the water during their turn. Aku'Tal otherwise functions as normal: each head can make only one Attack and all heads share the same pool of Hit Points.

Aku'Tal makes as many bite attacks as it has heads.

Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 10 (1d10 + 5) piercing damage.

A head of Aku'Tal can replace its bite Attack with a casting of the spell Sacred Flame (DC 16) 2d8 Radiant damage.