Adult Green Dragon
Huge Dragon, lawful evil
13,000 XP
Special Abilities
Amphibious
The dragon can breathe air and water.
Legendary Resistance (3/Day)
If the dragon fails a saving throw, it can choose to succeed instead.
Actions
Multiattack
The dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.
Bite
Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 6) piercing damage plus 7 (2d6) poison damage.
Claw
Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) slashing damage.
Tail
Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 15 (2d8 + 6) bludgeoning damage.
Frightful Presence
Each creature of the dragon's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 16 Wisdom saving throw or become frightened 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. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dragon's Frightful Presence for the next 24 hours.
Poison Breath (Recharge 5-6)
The dragon exhales poisonous gas in a 60-foot cone. Each creature in that area must make a DC 18 Constitution saving throw, taking 56 (16d6) poison damage on a failed save, or half as much damage on a successful one.
Legendary Actions
Detect
The dragon makes a Wisdom (Perception) check.
Tail Attack
The dragon makes a tail attack.
Wing Attack (Costs 2 Actions)
The dragon beats its wings. Each creature within 10 ft. of the dragon must succeed on a DC 19 Dexterity saving throw or take 13 (2d6 + 6) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.
Quick Reference
Running This Encounter
An Adult Green Dragon is a cunning, intelligent predator that prefers manipulation and deception before direct combat. Use its legendary actions to control the battlefield, moving in and out of melee while using its poisonous breath weapon against clustered targets. Leverage its high AC and regeneration (10 HP/turn) to wear down the party, and don't hesitate to flee if reduced below 100 HP to fight another day. Set traps, minions, and difficult terrain in its lair to maximize its advantages.
Combat Tactics
The dragon opens with poisonous breath on tightly grouped enemies, then uses Multiattack to focus fire on the weakest or most dangerous party member. It uses its legendary move to reposition out of melee range, forcing the party to chase it while it uses its lair actions (if in its den) to summon swarms or manipulate the environment.
Environment & Setting
An Adult Green Dragon thrives in dense forests, swamps, or underground caverns where it can hide in vegetation and use tight spaces to its advantage. Its lair should include shallow water, choking vines, and multiple levels to exploit its flying capability.