Ancient Blue Dragon

Stat block

Cha

21

Con

27

Dex

10

Int

18

Str

29

Wis

17

Speed

40 ft., burrow 40 ft., fly 80 ft.

Senses

blindsight 60 ft., darkvision 120 ft., passive Perception 27

Skills

Perception +17, Stealth +7

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. 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.

Languages

Common, Draconic

Saving throws

DEX +7, CON +15, WIS +10, CHA +12

Damage immunities

lightning

Legendary actions

• Legendary Actions. The ancient blue dragon can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. It 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.

Special abilities

• Legendary Resistance. If the dragon fails a saving throw, it can choose to succeed instead.