Hold Breath. The chroma hydra can hold its breath for 1 hour.

Multiple Heads. The chroma 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, roll a D6 as one of its heads dies. 1- Red, 2 - White, 3 - Green, 4 - Blue, 5 - Black, 6 - Reroll. If all its heads die, the hydra dies.

At the end of its turn, it a new head for each of its heads that died since its last turn, unless it takes a type of damage opposing the slain head. Red: Acid. White: Fire. Green: Cold. Blue: Poison. Black: Lightning. 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. While the hydra sleeps, at least one of its heads is awake.

Legendary Resistance  (3/day). If the Chroma Hydra fails a saving throw, it can choose to success instead.

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.

Multibreath (Recharge 5-6, 2nd success). The Chroma Hydra may make two consecutive breath attacks, provided it has at least two active heads. Roll to determine which breath attacks it makes, rerolling for any slain heads.

Fire Breath (1). The Chroma Hydra exhales fire in a 30-foot cone. Each creature in that area must make a DC 17 Dexterity saving throw, taking 42 (10d6) fire damage on a failed save, or half as much damage on a successful one.

Frost Breath (2). The Chroma Hydra exhales an icy blast in a 30-foot cone. Each creature in that area must make a DC 15 Constitution saving throw, taking 42 (12d6) cold damage on a failed save, or half as much damage on a successful one.

Poison Breath (3). The Chroma Hydra exhales poisonous gas in a 30-foot cone. Each creature in that area must make a DC 14 Constitution saving throw, taking 42 (12d6) poison damage on a failed save, or half as much damage on a successful one.

Lightning Breath (4). The Chroma Hydra exhales lightning in a 60-foot line. Each creature in that area must make a DC 14 Dexterity saving throw, taking 42 (12d6) lightning damage on a failed save, or half as much damage on a successful one.

Acid Breath (5). The Chroma Hydra exhales acid in a 30-foot line. Each creature in that area must make a DC 14 Dexterity saving throw, taking 42 (12d6) acid damage on a failed save, or half as much damage on a successful one.

Chromatic Breath (6). The Chroma Hydra collects its heads together and pool their breath weapons together into a fearsome, chaotic ray of energy. One of the heads die after this attack. The target creature must make a DC 16 Dexterity saving throw. On a failed save, the target takes 10d6 + 20 force damage. If this damage reduces the target to 0 hit points, it is disintegrated. A disintegrated creature and everything it is wearing and carrying, except magic items, are reduced to a pile of fine gray dust. The creature can be restored to life only by means of a true resurrection or a wish spell. This spell automatically disintegrates a Large or smaller nonmagical object or a creation of magical force. If the target is a Huge or larger object or creation of force, this spell disintegrates a 10-foot-cube portion of it. A magic item is unaffected by this spell.