Gray Dragon, Ancient

Family: Dragon - Gray

Gargantuan dragon, neutral evil

Armor Class 21 (natural armor)
Hit Points 455 (26d20 + 182)
Speed 40 ft., fly 80 ft., swim 40 ft.

STR	DEX	CON	INT	WIS	CHA
28 (+9)	14 (+2)	25 (+7)	19 (+4)	19 (+4)	19 (+4)

Saving Throws Dexterity +9, Constitution +14, Wisdom +11, Charisma +11
Skills Perception +18, Stealth +9
Damage Immunities fire
Senses blindsight 60 ft., darkvision 120 ft., passive Perception 28
Languages Abyssal, Aquan, Common, Draconic, Giant
Challenge 21 (33,000 XP)

Special Traits

• 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 uses its Frightful Presence and makes three attacks: one with its bite and two with its claws.
• Bite. Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 20 (2d10 + 9) piercing damage plus 7 (2d6) fire damage.
• Claw. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit: 16 (2d6 + 9) slashing damage.
• Tail. Melee Weapon Attack: +16 to hit, reach 20 ft., one target. Hit: 18 (2d8 + 9) 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 20 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 of 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 90-foot cone. Creatures in the area must make a DC 22 Constitution saving throw. On a failed saving throw, the creature takes 80 (23d6) fire damage, or half as much damage on a successful saving throw. Being underwater doesn’t grant resistance to this damage.

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.

• 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 15 feet of the dragon must succeed on a DC 24 Dexterity saving throw or take 16 (2d6 + 9) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.

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:

• Dead Water. A 30-foot cube of water the dragon can see within 120 feet of it stagnates and becomes unable to support life of any kind. Aquatic creatures or creatures benefiting from spells such as water-breathing cannot survive in the area and begin suffocating. The dragon can end this effect at any time.
• Steam Cloud. The dragon causes an area of water within 120 feet of it to superheat, creating a cloud of fog in a 60-foot radius sphere. The sphere spreads around corners and its area is heavily obscured. The fog cloud remains for 1 hour or until a wind of moderate or greater speed (at least 10 miles per hour) disperses it.
• Control Water. The dragon can cause an area of water to act as if the spell control water was cast on it. The dragon does not have to concentrate on this effect, and it remains active for the duration or until the dragon dismisses it (no action required).

Regional Effects

The region containing the ancient gray dragon’s lair is changed by its presence, which creates one or more of the following effects: Obscuring Fog. Twenty-foot areas of fog and steam dot the landscape within 6 miles of the lair. These areas are heavily obscured.

Heavy Tides. Tides are supernaturally heavy and inundate coastal areas, causing massive flooding. If the dragon dies, these effects fade over 1d10 days.