Chromalgeam

Blood Colour. The chromalgeam turns to the colour of its immediate surroundings and can only use abilities tagged with its current colour.

Camouflage. The chromalgeam gets a +10 to hide checks.

Blood Spray. Whenever the chromalgeam is hit with a slashing or piercing attack and has 90 hit points or fewer, it spews its magical blood from the cut. Any creature within 5 feet of the attacked area must make a DC 16 Dexterity saving throw, or be subjected to one of the following effects, depending on the current colour of its blood:

Red. The creature takes 6d6 fire damage.

Orange. The creature takes 6d6 acid damage.

Yellow. The creature is paralysed by lightning.

Green. The creature is poisoned.

Blue. The creature is frozen solid and petrified.

Indigo. The creature turns to stone and is petrified for up to 24 hours.

Violet. The creature is blinded.

Multiattack. The chromalgeam can make two non-breath attacks.

Claws. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: (3d6 + 4) slashing damage. 

Tongue. Ranged Weapon Attack: +7 to hit, range 20/40 ft., one target. Hit: (1d6 + 4) bludgeoning damage, and the target is grappled (escape DC 14). Until this grapple ends, the target is restrained, and the chromalgeam can't use this attack on another target.

Fire Breath (Red) (Recharge 5-6). The chromalgeam exhales fire in a 30-foot cone. Each creature in that area must make a DC 14 Dexterity saving throw, taking (10d6) fire damage on a failed save, or half as much on a successful one.

Acid Spray (Orange) (Recharge 5-6). The chromalgeam exhales a spray of acid in a line that is 60 feet long and 5 feet wide. Each creature in that area must make a DC 14 Dexterity saving throw, taking (10d6) acid damage on a failed save, or half as much on a successful one.

Lightning Breath (Yellow) (Recharge 5-6). The chromalgeam exhales lightning in a line that is 60 feet long and 5 feet wide. Each creature in that area must make a DC 14 Dexterity saving throw, taking (10d6) lightning damage on a failed save, or half as much on a successful one.

Poison Breath (Green) (Recharge 5-6). The chromalgeam exhales poisonous gas in a 30-foot cone. Each creature in that area must make a DC 14 Constitution saving throw, taking (10d6) poison damage on a failed save, or half as much on a successful one.

Cold Breath (Blue) (Recharge 5-6). The chromalgeam exhales an icy blast in a 30-foot cone. Each creature in that area must make a DC 14 Constitution saving throw, taking (10d6) damage on a failed save, or half as much on a successful one.

Petrifying Breath (Indigo) (Recharge 5-6). The chromalgeam exhales petrifying gas in a 30-foot cone. Each creature in that area must succeed on a DC 14 Constitution saving throw. On a failed save, a target begins to turn to stone and is restrained. The restrained target must repeat the saving throw at the end of its next turn. On a success, the effect ends on the target. On a failure, the target is petrified until freed by the greater restoration spell or other magic.

Blinding Breath (Violet) (Recharge 5-6). The chromalgeam exhales a flash of light in a 30-foot cone. Each creature in that area must make a DC 14 Constitution saving throw. On a failed save, a target's vision begins to fade. The target must repeat the saving throw at the end of its next turn. On a success, the effect ends on the target. On a failure, the target is blinded until freed by magic.

Misty Escape (3/Day). After being hit by an attack, the chromalgeam can teleport up to 40 feet to an unoccupied space it can see and can attempt to camouflage (hide) upon entering the space.

Prismatic Absorption. When hit with an attack of fire, acid, lightning, poison or cold damage, or subjected to stone petrification or blindness, the chromalgeam can choose to swallow the elemental damage, taking no damage and instead regaining a number of hit points equal to the elemental damage dealt (for petrification or blindness, the chromalgeam gains 20 hit points). The chromalgeam then turns the corresponding colour of the damage/condition absorbed (fire - red) (acid - orange) (lightning - yellow) (poison - green) (cold - blue) (petrified - indigo) (blindness - violet) for 6 seconds, until reverting back to the colour of its immediate surroundings.