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

Shrink. As a bonus action the elysian dragon can shrink up to 3 size categories smaller than their current size. Whilst they are smaller than normal they retain their general shape but per each size category smaller their strength stat is reduced by 4 points. And using their bonus action again can become normal size once more.

Innate Spellcasting. The adult elysian dragon's innate spellcasting ability is Wisdom (DC 16). The adult elysian dragon can innately cast the following spells, requiring no material components:

at will: create food and drink, tasha's hideous laughter

3/day: calm emotions, polymorph

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

Bite. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 6) piercing damage.

Claw. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) slashing damage.

Tail. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 15 (2d8 + 6) 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 15 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.

Breath Weapons (Recharges 5/6). The dragon uses one of the following breath weapons.

Sonic breath. The elysian dragon exhales a line of sonic vibrations in a 90ft long, 5ft wide. Each creature within the line must make a DC 18 Dexterity saving throw or take 45 (13d6) thunder damage. On a successful saving throw a creature takes half damage.  

Inebriation gas breath. The elysian dragon exhales a light blue inebriating gas in a 60ft cone. Each creature within the radius must make a DC 18 Constitution saving throw or be under an effect identical to the poisoned condition but also have advantage on all fear based saves and is upbeat and very happy. 

The adult elysian 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 adult elysian 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.

"Happy stuff" (Costs 2 Actions). The elysian dragon creatures a swirling cloud of pink gas around them in a 30ft radius centered on themselves. Each creature within range must make a DC 18 Charisma saving throw or be charmed by the elysian dragon for 1 minute.