Hold Breath. The hydra can hold its breath for 1 hour. This ability only applies if one of the hydras heads comes from a beast with a swimming speed (including animals that in reality are excellent swimmers but lack stat blocks).

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, and knocked unconscious.

whenever the hydra takes 25 or more damage in a single turn, one of its heads dies. If all of its heads die, the hydra dies.

At the end of its turn, it grows back two heads for each of its heads that died last turn, unless the stump was cauterized with salt 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. When the hydra sleeps, at least one of its heads is awake.

Multiattack. The hydra can make as many head attacks as it has heads.

Wolf Head. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 10 (1d10 + 5) piercing damage. If the target is a creature, it must succeed on a DC 14 Strength saving throw or be knocked prone.

Giraffe Head. Melee Weapon Attack: +8 to hit, reach 30 ft., one target. Hit: 10 (1d10 + 5) bludgeoning damage.

Penguin Head. The penguin exhales a blast of frigid air in a 15-foot cone. Each creature in that area must make a DC 14 Constitution saving throw, taking 20 (4d8) cold damage on a failed save, or half as much on a successful one.

Komodo Dragon Head. Melee Weapon Attack: +8 to hit,, reach 10 ft., one target. Hit: 10 (1d10 + 5) piercing damage. If the target is a creature, it must succeed on a DC 14 Constitution saving throw or gain one level of exhaustion.

Gorilla Hand. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 10 (1d10 + 5) bludgeoning damage. If the target is a creature wielding a weapon the hand can forgoe dealing  damage and instead disarm them, any future attacks made by the hand use the statistics of the stolen weapon until it is destroyed or disarmed itself.

Rhinoceros Head. Melee Weapon Attack: +8 hit, reach 10 ft., one target. Hit: 17 (2d8 + 5) piercing damage.

Parrot Head. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 9 (1d2 + 5) piercing damage. This head can forgoe biting and instead innately cast the Vicious Mockery spell.

Lion Head. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 10 (1d10 + 5) piercing damage. This head can forgoe biting and instead roar. Any creature that hears the roar must succeed on a DC 14 Wisdom saving throw or become frightened of the hydra for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. 

Crocodile Head. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 10 (1d10 + 5) piercing damage, and the target is grappled (escape DC 14). Until this grapple ends, the target is restrained, and the head can't bite another target.