Manchineel Dragon

Traits

Deadly Chemicals. When the dragon takes Fire damage, the flames ignite the toxins coating its scales creating a 40-foot-radius Sphere of poisonous smoke centered on the dragon that remains until the end of the dragon's next turn. Each creature in that area must make a DC 25 Constitution saving throw. On a failure, that creature is Poisoned and Blinded for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

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

Toxic Sap. A creature that touches the dragon or hits it with a melee attack while within 5 feet of it takes 10 (3d6) Acid damage.

Actions

Multiattack. The dragon can use its Vengeful Floral Presence. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Attack Roll: +18, reach 15 ft. Hit: 32 (4d10 + 10) Piercing damage plus 14 (4d6) Acid damage.

Claws. Melee Attack Roll: +18, reach 10 ft. Hit: 24 (4d6 + 10) Slashing damage.

Tail. Melee Attack Roll: +18, reach 20 ft. Hit: 28 (4d8 + 10) Bludgeoning damage.

Vengeful Floral Presence. The dragon enters a battle frenzy, driven by the ages-old fury inside it. Wisdom Saving Throw: DC 21, each creature of the dragon's choice within 120 feet. Failure: A creature is vulnerable to all damage from the dragon's attacks, and makes attack rolls against the dragon with Advantage. These effects last for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effects on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dragon's Vengeful Floral Presence for the next 24 hours.

Legendary Actions

The dragon can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The dragon regains spent legendary actions at the start of its turn.

Lock Horns. The dragon chooses one creature within 15 feet of it that it can see. The target must make a contested Strength (Athletics) check against the dragon's Strength (Athletics) check. If the dragon wins the contest, the target is pushed back up to 15 feet away from it to an unoccupied space. If the dragon wins the contest by 10 or more, the creature is sent flying and lands Prone in the unoccupied space. If the target wins the contest, it can push the dragon up to 15 feet away from it to an unoccupied space.

Tail. The dragon makes a tail attack.

Rampage (Costs 2 Actions). The dragon moves up to its speed in a straight line without provoking Opportunity Attacks. Each creature in its path is targeted once by the following effect. Dexterity Saving Throw: DC 26. Failure: 19 (3d12) Bludgeoning damage and the target has the Stunned condition until the start of the dragon's next turn.

A Manchineel Dragon's Lair

Any area a manchineel stays in is quickly corrupted and becomes its lair. The ground, water, and air fill with its acrid poison.
Lair Actions. While fighting in its lair, the manchineel dragon is empowered by its poisonous miasma. On initiative count 20 (losing initiative ties), the dragon takes a lair action to cause one of the following effects; the dragon can't use the same effect two rounds in a row.

• The dragon burrows up to its speed. All creatures in its path or on the surface above its path must succeed on a DC 26 Dexterity saving throw or be knocked Prone.
• Manchineel plants in the lair drip toxic sap. Each creature in the lair must make a DC 25 Dexterity saving throw or take 21 (6d6) Acid damage, or half as much damage on a success.
• Patches of ground within 90 feet of the dragon become unstable and crumble. Creatures in a 20-foot square area of the dragon's choice must succeed on a DC 25 Dexterity saving throw or fall into a 20-foot-deep hole and take 7 (2d6) Bludgeoning damage.

Regional Effects. The region containing a manchineel dragon's lair is warped by the dragon's magic, which creates one or more of the following effects:

• When it rains, the area within 1 mile of the dragon's lair experiences acid rain.
• The ground within 1 mile of the lair has large, deep holes from the dragon's burrowing.
• Fruit and vegetables grown within 20 miles of the dragon's lair have an acidic aftertaste, though they are not poisonous themselves.

If the dragon dies, these effects fade over the course of 1d10 days.