Adult Red Dragon

Adult Red Dragon CR: 17 (18000 XP)

Huge dragon, chaotic evil

Armor Class: 19 (natural armor)

Hit Points: 256 19d12+133

Speed: 40 ft , fly: 80 ft , climb: 40 ft

STR

27 +8

DEX

10 +0

CON

25 +7

INT

16 +3

WIS

13 +1

CHA

21 +5

Saving Throws: Dex +6, Con +13, Wis +7, Cha +11

Skills: Perception +13, Stealth +6

Damage Immunities: Fire

Senses: Blindsight 60 ft., darkvision 120 ft, passive Perception 23.

Languages: Common, Draconic

Challenge Rating: 17 (18000 XP)

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: +14 to hit, reach 10 ft., one target. Hit: 2d10+8 piercing damage plus 2d6 fire damage.
Claw Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit: 2d6+8 slashing damage.
Tail Melee Weapon Attack: +14 to hit, reach 15 ft., AOE. Hit: 2d8+8 bludgeoning damage.
Frightful Presence Each creature of the dragon's choice that is within 120 ft. of the dragon and aware of it, must succeed on a DC 19 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.
Fire Breath (Recharge 5-6) The dragon exhales fire in a 60-foot cone. Each creature in that area must make a DC 21 Dexterity Saving Throw, taking 18d6 fire damage on a failed save, or half as much on a successful one.

Legendary Actions

The adult red dragon can take 3 Legendary Actions per turn, which replenish at the start of its turn. These can only be taken at the end of another creature's turn, only one at a time.

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 22 Dexterity Saving Throw or take 2d6+8 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:

• Magma erupts from a point in the ground the dragon can see within 120 feet of it, creating a 20 foot high, 5 foot radius geyser. Each creature in the geyser's area must make a DC 15 Dexterity saving throw, taking 21 6d6 fire damage on a failed save, or half the damage on a successful one.
• A tremor shakes the lair in a 60 foot wide radius around the dragon. Each creature other than the dragon on the ground in that area must succeed on a DC 15 Dexterity saving throw or be knocked prone.
• Volcanic gases form a cloud in a 20 foot radius sphere centred on a point the dragon can see within 120 feet of it. The sphere spreads around corners, and it's area is lightly obscured. It lasts until initiative count 20 on the next round. Each creature that starts it's turn in the cloud must make a DC 13 Constitution saving throw or be poisoned until the end of it's turn. When poisoned in this way, a creature is incapacitated.

Red dragons lair in high mountains or hills, dwelling in caverns under snow-capped peaks, or within the deep halls of abandoned mines dwarven strongholds. Caves with volcanic ort geothermal activity are the most highly prized red dragon lairs, creating hazards that hinder intruders and searing heat and volcanic gases wash over a dragon as it sleeps.
With it's hoard well protected deep within it's lair, a red dragon spends as much of it's time outside mountain as in it. For a red dragon, the great heights of the world are the throne from which it can look out to survey all it controls - and the wider world it seeks to control.
Throughout the lair complex, servants erect monuments to the dragon's power , telling the grim story of it's life, the enemies it has slain, and the nations it has conquered.

Regional Effects

The region containing a legendary red dragon's lair is warped by the dragon's magic, which creates one or more of the following effects:

• Small earthquakes are common within 6 miles of the dragon's lair.
• Water sources within 1 mile of the lair are supernaturally warm and tainted by sulphur.
• Rocky fissures within 1 mile of the dragon's lair form portals to the Elemental Plane of Fire, allowing creatures of elemental fire into the world to dwell nearby.

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

Adult red dragons are nightmares to face. Strong powerful and highly dangerous, they have centuries of experience and will do anything to dominate surrounding regions. This also applies to it's treasure hoard, and knows where all it's treasure is in it's cave.

Suggested Environments

Mountains, hills, cave lair.