Monster
Ancient Blue Dragon
Gargantuan dragon, lawful evil
- Armor Class
- 22 (natural armor)
- Hit Points
- 481 (26d20 + 208)
- Speed
- 40 ft., burrow 40 ft., fly 80 ft.
- STR
- 29 (+9)
- DEX
- 10 (+0)
- CON
- 27 (+8)
- INT
- 18 (+4)
- WIS
- 17 (+3)
- CHA
- 21 (+5)
- Saving Throws
- Dex +7, Con +15, Wis +10, Cha +12
- Skills
- Perception +17, Stealth +7
- Damage Immunities
- lightning
- Senses
- blindsight 60 ft., darkvision 120 ft., passive Perception 27
- Languages
- Common, Draconic
- Challenge
- 23 (50,000 XP)
- Proficiency Bonus
- +7
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: +16 to hit, reach 15 ft., one target. Hit: 20 (2d10 + 9) piercing damage plus 11 (2d10) lightning 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 or the effect ends for it, the creature is immune to the dragon's Frightful Presence for the next 24 hours.
Lightning Breath (Recharge 5-6). The dragon exhales lightning in a 120-foot line that is 10 feet wide. Each creature in that line must make a DC 23 Dexterity saving throw, taking 88 (16d10) lightning damage on a failed save, or half as much damage on a successful one.
Legendary Actions
The ancient blue 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 ancient blue 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 ft. 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.