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.
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 4 (1d8) acid 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.
Steam Breath (Recharge 5–6). The dragon exhales steam in a 60-foot cone. Each creature in that line must make a DC 18 Dexterity saving throw, taking 54 (12d8) burn damage on a failed save, or half as much damage on a successful one.
Boil Water. Concentration up to 1 minute. The dragon magically boils a pool of water it can see within 120 feet, up to 15-foot-radius of water. Each creature in boiling water must make a DC 18 Constitution saving throw, taking 24 (4d8) burn damage on a failed save, or half as much damage on a successful one. Creatures who start their turn in the boiling water take 12 (2d8) burn damage.
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.
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 feet 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.
Lair and Lair Actions
Gray dragons dwell in cavernous mountains or hills near swamps or large bodies of water. A gray dragon’s lair is a vast cave, grotto, or ruin that has pockets of hot spring pools where the dragon rests, and where its victims can boil. The lair is warm and often foggy. Bats, rats, and snakes infest the lair, which is filled with the scent of boiled meat and musty creatures.
Lair Actions
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:
- Pools of water that the dragon can see within 120 feet of it surge outward in a grasping tide. Any creature on the ground within 20 feet of such a pool must succeed on a DC 15 Strength saving throw or be pulled up to 20 feet into the water and knocked prone.
- Magical steam fog billows around all creatures in a 20-foot-radius sphere the dragon can see within 120 feet of it. The creatures must succeed on a DC 15 Wisdom saving throw or be charmed by the dragon until initiative count 20 on the next round. Charmed creatures have a strong desire to bathe in one of the lair's hot pools, and must pass a DC 10 Wisdom saving throw at the beginning of their turn to not move toward the nearest pool. If the creature arrives a pool, it will enter and sit to bathe.
- Magical darkness spreads from a point the dragon chooses within 60 feet of it, filling a 15-foot-radius sphere until the dragon dismisses it as an action, uses this lair action again, or dies. The darkness spreads around corners. A creature with darkvision can’t see through this darkness, and nonmagical light can’t illuminate it. If any of the effect’s area overlaps with an area of light created by a spell of 2nd level or lower, the spell that created the light is dispelled.
Regional Effects
The region containing a legendary gray dragon’s lair is warped by the dragon’s magic, which creates one or more of the following effects:
- The land within 10 miles of the lair takes twice as long as normal to traverse, since the plants grow thick and twisted, and the swamps are thick with reeking mud.
- Water sources within 6 mile of the lair are supernaturally warmed. Enemies of the dragon that drink such water regurgitate it within minutes. Allies of the dragon that bathe in a hot spring gain 4d4 temporary HP.
- Fog lightly obscures the land within 10 miles of the lair. The fog is thick in the mornings and obscures vision to 10 feet, but dissipates by noon to obscure visibility beyond to 40 feet. Dissipation within forests takes longer.
If the dragon dies, vegetation remains as it has grown, but other effects fade over 1d10 days.
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