Adult Blue Dragon

3/day. If the adult blue dragon fails a saving throw, it can choose to succeed instead.

3 legendary actions; one at a time at the end of another creature’s turn, regaining spent uses at the start of its turn

Melee Weapon Attack: +12 to hit, reach 10 ft.. Hit: 18 (2d10 + 7) piercing plus 5 (1d10) lightning damage.

Melee Weapon Attack: +12 to hit, reach 5 ft.. Hit: 14 (2d6 + 7) slashing damage.

The adult blue dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Each creature of the adult blue dragon's choice that is within 120 ft. of the dragon and aware of it must succeed on a DC 17 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 adult blue dragon's Frightful Presence for the next 24 hours.

Melee Weapon Attack: +12 to hit, reach 15 ft.. Hit: 16 (2d8 + 7) bludgeoning damage.

Recharge 5–6. The adult blue dragon exhales lightning in a 90-foot line (5 ft. wide). Each creature in that line must make a DC 19 Dexterity saving throw, taking 66 (12d10) lightning damage on a failed save, or half as much damage on a successful one.

The adult blue dragon makes a Wisdom (Perception) check.

The adult blue dragon makes a tail attack.

Costs 2 legendary actions. The adult blue dragon beats its wings. Each creature within 10 ft. of the adult blue dragon must succeed on a DC 20 Dexterity saving throw or take 14 (2d6 + 7) bludgeoning damage and be knocked prone. The adult blue dragon can then fly up to half its flying speed.