Blind song. All hostile creatures that can hear the false hydra must make a DC13 Wisdom saving throw at the start of their turn. This DC increases by 2 for each additional head the hydra uses to sing. On a failed saving throw, the target has their memory wiped of the false hydra’s existence, any information that links to the false hydra and any additional information the false hydra chooses. The false hydra can only wipe additional information if the false hydra knows the creature possesses it. The creature also cannot perceive the false hydra (can’t see it, hear it, smell it, etc.) or anything the false hydra is holding, wearing, or any information linked to it. Only abilities that grant true sight can see through this ability.

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

Whenever the false hydra takes 50 or more damage in a single turn, one of its heads dies. If all its heads die, the false hydra dies.

At the end of its turn, it regrows a head to a maximum of five heads, unless it has taken fire damage since its last turn. The false hydra regains 20 hit points for each head regrown in this way. 

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

Spider Climb. The false hydra can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Multiattack. The false hydra makes as many bite attacks as it has heads and can use a claw attack. 

Bite. Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 9 (1d10 + 3) piercing damage.

Claw: Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: The target is grappled (escape DC 15). Until the grapple ends, the target is restrained.

Sing. The false hydra can use a bonus action to stop singing or to start its song with a  head. 

Reactive Heads. For each head the false hydra has beyond one, it gets an extra reaction.

Wail. After taking damage, the false hydra van use a reaction to wail. Creatures within 10ft of the hydra when it wails take 1d4 psychic damage.