Adult Kendermore Blue Dragon

Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Building Charge. When the dragon rolls to recharge its lightning breath, creatures within 10 feet of it take 1d6 lightning damage. If the dragon succesfully recharges its lightning breath, creatures within 5 feet of it take an additional 1d6 lightning damage.

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 15 ft., one target. Hit: 23 (4d6 + 9) piercing damage plus 13 (2d12) lightning damage.

Claw. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 20 (2d10 + 9) slashing damage.

Tail. Melee Weapon Attack: +14 to hit, reach 20 ft., one target. Hit: 21 (2d12 + 9) bludgeoning damage.

Horn. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 18 (2d8 + 9) piercing damage + 9 (2d8) lightning 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 95-­foot line that is 10 feet wide. Each creature in that line must make a DC 22 Dexterity saving throw, taking 93 (17d10) lightning damage on a failed save, or half as much damage on a successful one.

Innate Spellcasting. The dragon's spellcasting ability is Charisma (spell save DC 19, +12 to hit with spell attacks). The dragon can innately cast the following spells, requiring only verbal components:

At Will: thaumaturgy, lightning lure, magic missile, create or destroy water, shield

2/day each: major image, thunder step, slow, arcane eye, wall of stone, telekinesis, forcecage

4/day: chain lightning, programmed illusion, etherealness

Discharge. As a reaction to passing a saving throw against a spell, the dragon may force the spell's caster to take 1d10 lightning or force damage (dragon's choice) per level of the spell.

Gather Charge. As a reaction to being reduced below 124 HP, the dragon moves up to its walk or burrow speed. If it is hit with an attack in the course of this movement, it may immediately roll to recharge one of its breath weapons. It may move through creations of magical force with this movement, destroying them.

Sandlash. As a reaction to being hit with an attack, the dragon may force the attacker to make a DC 19 Constitution saving throw or be blinded until the end of the dragon's next turn.

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.

Ionic Attunement. One creature within 60 feet must make a DC 21 Constituion saving throw or lose any lightning resistance that it has and suffer disadvantage on its next Dexterity saving throw in the next minute.

Wing Attack (Costs 2 Actions). The dragon beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 23 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.