Candycane Hydra

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 is immuned to being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Whenever the hydra takes 30 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 20 fire damage since its last turn. The hydra regains 15 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.

Candyflage. While the Hydra is standing still it is indistinguishable from giant ominous candycanes. When the Hydra breaks out of candyflage, each creature that was not aware of it makes a wisdom saving throw (DC15) or become frightened for 1 minute. A creature can repeat this saving throw at the end of each of it's turns, ending the effect on a succesful save.
If a creature succeeds on it's saving throw it is immune to this effect for the next 24 hours.

Frightful Presence. When the Hydra breaks out of candyflage, each creature that was not aware of it makes a wisdom saving throw (DC15) or become frightened for 1 minute. A creature can repeat this saving throw at the end of each of it's turns, ending the effect on a succesful save.
If a creature succeeds on it's saving throw it is immune to this effect for the next 24 hours.

Caramel. When the hydra takes fire damage it spills some of it's molten candy onto the ground. Each creature within 10ft. of the hydra must succeed on a DC 17 DEX save, taking 2D6 fire dmg or half as much on a succesful save.

Legendary Resistance (3/Day). If the hydra fails a saving throw, it can choose to succeed instead.

Multiattack. The hydra makes as many bite attacks as it has heads.

Bite. Melee weapon attack: +10 to hit. Reach 10ft. 1 target, hit 1D6+6 piercing dmg + 1D6 cold dmg.

Grapple. The hydra forgoes on of his bite attacks to attempt to grapple a target.

Swallow. The hydra makes a bite attack against a grappled creature (Melee weapon attack: +10 to hit. Reach 10ft. 1 target, hit 1D6+6 piercing dmg + 1D6 cold dmg). On a hit the creature is swallowed by the hydra. While the target is inside the hydra it is blinded, restrained and has total cover against all attacks.
If you start your turn inside the hydra you take 4D6 acid dmg. Ifthe hydra takes 15 dmg or more from the creature inside it, it must succeed on a DC 25 CON saving throw or regurgitate all swallowed creatures, which fall prone in an area around of 10ft. around the hydra.
When the hydra dies all swallowed creatures are no longer restrained and can spend 15ft. of movement speed to exit the hydra prone.

Candy-gunk Shot. For each head choose a 5ft. area (connected to each other). Creatures in that area must succeed on a DC 16 DEX save or become restrained and take 5D6 acid dmg. On a succesful save the target is not restrained and takes half dmg. 
The area covered in gunk is difficult terrain for 10 minutes.

Legendary actions:

Move up to normal movement speed. (1 action)

Move to another pool of water through an underwater tunnel (1 action)

The hydra makes a perception check (1 action)

Make 2 bite attacks (1 action)

Regrow 2 heads immediatly if the hydra hasn't taking fire damage since the last turn(2 actions)

Bite. Melee weapon attack: +10 to hit. Reach 10ft. 1 target, hit 1D6+6 piercing dmg + 1D6 cold dmg.

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