Coral Hydra (Solo threat)

Amphibious. The Coral Hydra can breathe air and water.

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 its heads die, the hydra dies.

At the start of its turn, it grows two heads for each of its heads that died since its last turn, unless it has taken acid damage 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.

Reflective Mucus: The Coastal Hydra is surronded by a mucus that have a shimmering, reflective quality that can occasionally deflect magical energy. Whenever the hydra is targeted by a magic missile spell, line spell or spell attack roll, roll a d6. On a 6, the spell is reflected back at the caster as if it originated from the hydra, turning the caster into the target.

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

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

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

Lashing Retaliation: When a creature hits the hydra with a melee attack, it can immediately make a Bite attack against that creature if it is within its reach.

Villain Actions. The Coastal Hydra has three villain actions. They can take each action once during an encounter after an enemy’s turn. They can take these actions in any order but can only use one per round.

1. Tidal Slam: On its turn, the hydra can slam its body into the ground or water, causing a small tidal wave in a 20-foot radius centered on itself. All creatures in that area must make a DC 15 Strength saving throw or be knocked prone and take 2d8 bludgeoning damage.

2. Rejuvenating Mist: Emit a rejuvenating mist from its body, healing itself for 2d10 hit points and causing all enemies within 10 feet to become enshrouded in a foggy mist, giving them disadvantage on attack rolls until the end of their next turn.

3. Hydra's Fury: The hydra can make an immediate bite attack against every enemy within its reach.