Blind Song. All hostile creatures that can hear the Hydra sing must make a DC15 Wisdom saving throw at the start of their turn. If the Hydra sings with more than one head, all hostile creatures must subtract 1d4 from their saving throw. On a failure, the creature forgets the Hydra is there.

Sing. The Hydra can use a bonus action to stop singing or to start its song with an additional head.

Multiple Heads. The Young False Hydra has 6 heads that can be attacked seperately. If a head takes 35 damage or more, it is killed. Creatures within 5ft range of the killed head must make a DC10 Dexterity saving throw or be knocked prone. 
One of the heads is larger and will act as the primary. This head will never stop singing and will have the other heads protect it. If this head is destroyed, one of the others will grow larger and will assume the position of primary.

Regrowth. The False Hydra can use a bonus action to begin regrowing a head that has died. It takes two Regrowth bonus actions to fully regrow a head. It regains 20 hit points each time it uses Regrowth.

Legendary Resistance (1/Day). If the Young False Hydra fails a saving throw, it can choose to succeed instead.

Extended Neck The false hydra's heads have a sickeningly long neck. Each head can extend several hundred feet from it's body.

A head can recoil into it's body or shoot out to the full range as a move action. The heads movement can provoke an attack of opportunity and all parts of the head and neck can be targeted if extended. These opportunity attacks are made with advantage.

Multiattack. The Hydra can use a claw attack or a bite attack on its turn, up to three attacks per round

Bite. Melee Weapon Attack: +5 to hit, reach 15 ft., one target. Hit: 8 (1d8+3) piercing damage. 

Claws. Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 7 (1d6+3) slashing damage. If the Hydra succeeds on a claw attack, it can choose to grapple the target instead of dealing damage. (The hydra can only grapple one creature at a time and cannot use its claw attack while grappling a creature.)

Wail. The False Hydra can combine three heads and make a unison attack. The three heads will combine three attacks into one wail, dealing 15 (5d6) psychic damage. Once used the Hydra cannot use this attack for 1 turn. 

Multireact. The Hydra can make two reactions per round 

Mimicry - Wail. After taking damage, the Hydra can use a reaction to mimic the voice of one of the people it has consumed, crying out for help. Creatures within 5ft of the Hydra when it wails take 2d4 psychic damage.

Mimicry - Morph. After a creature takes the attack action, the Hydra can focus its gaze upon that same creature and peer into their eyes. The creature must make a DC18 saving throw. On a failure, the creature will see the Hydra's face morph into the face of a loved one or someone from the creature's past. The creature must make all rolls with disadvantage next turn.
On a success, they are unaffected by the Hydra's gaze and the Hydra's face remains the same. 

End Song. If only one head remains, the Hydra will cast its face to the sky and let out a new song in desperation, in an attempt to overcome its foe(s). All hostile creatures must make a DC12 Wisdom saving throw. 

On a failure, the creature will be affected by Dominate Person for 2 turns. 

This action happens immediately when only one head remains and will automatically end the Blind Song