Multiattack. Lhammaruntosz can use her Frightful Presence. She then makes three attacks: one with her bite and two with her claws.

Bite. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 18 (2d10 + 7) piercing damage.

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

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

Frightful Presence. Each creature of Lhammaruntosz's choice that is within 120 feet of her and aware of her 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 Lhammaruntosz's Frightful Presence for the next 24 hours.

Breath Weapons (Recharge 5–6). Lhammaruntosz uses one of the following breath weapons.

Lightning Breath. Lhammaruntosz exhales lightning in a 90-foot line that is 5 feet 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.

Repulsion Breath. Lhammaruntosz exhales repulsion energy in a 30-foot cone. Each creature in that area must succeed on a DC 19 Strength saving throw. On a failed save, the creature is pushed 60 feet away from the dragon.

Change Shape. Lhammaruntosz magically polymorphs into a humanoid or beast that has a challenge rating no higher than her own, or back into her true form. She reverts to her true form if she dies. Any equipment she is wearing or carrying is absorbed or borne by the new form (Lhammaruntosz's choice). In a new form, Lhammaruntosz retains her alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary Resistance, lair actions, and Intelligence, Wisdom, and Charisma scores, as well as this action. Her statistics and capabilities are otherwise replaced by those of the new form, except any class features or legendary actions of that form.

Detect. Lhammaruntosz makes a Wisdom (Perception) check.

Tail Attack. Lhammaruntosz makes a tail attack.

Wing Attack (Costs 2 Actions). Lhammaruntosz beats its wings. Each creature within 10 feet of Lhammaruntosz must succeed on a DC 20 Dexterity saving throw or take 14 (2d6 + 7) bludgeoning damage and be knocked prone. Lhammaruntosz can then fly up to half her flying speed.