Ancient Space Dragon

Unusual Nature The dragon does not need to breathe.

Regeneration At the start of each of its turns, if the dragon has at least 1 hit point, it regains 35 hit points.

Curse of Sleep The dragon has disadvantage on saving throws against resisting falling asleep. Additionally, its hit points are considered to be 1/4th its current hit points for the purposes of the sleep spell.

Eternal and Unkillable When the dragon dies, its body turns to dust and its spirit can inhabit a nearby nonmagical object. While inhabiting an object in this way, the dragon cannot be killed or harmed. It can speak only telepathically and can take no actions other than its spellcasting ability.

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

Multiattack. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing damage.

Claw. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 17 (2d6 + 10) slashing damage.

Tail. Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: 19 (2d8 + 10) bludgeoning damage.

Acid Breath (recharge 5-6). The dragon exhales a cloud of acid in a 30 foot diameter sphere centered on a point it chooses within 30 feet of it. Each creature that enters the cloud for the first time on its turn or starts its turn in that area must make a DC 22 Constitution saving throw, taking 58 (13d8) acid damage on a failed save, or half as much damage on a successful one.

The cloud remains for 1 minute or until dispersed by a strong wind. The cloud is also highly flammable. If the cloud is exposed to an open flame, magical or otherwise, it ignites and explodes. Any creature within 10 feet of the area must make a DC 22 Dexterity saving throw, taking 72 (16d8) fire damage on a failure or half as much on a successful one. When this happens, the cloud ends.

Change Shape. The dragon magically polymorphs into a humanoid or beast that has a challenge rating no higher than its own, or back into its true form. It reverts to its true form if it dies. Any equipment it is wearing or carrying is absorbed or borne by the new form (the dragon's choice).

In a new form, the dragon retains its alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary Resistance, lair actions, and Intelligence, Wisdom, and Charisma scores, as well as this action. Its statistics and capabilities are otherwise replaced by those of the new form, except any class features or legendary actions of that form.

Spellcasting. The dragon casts the following spell, using its Charisma as the spellcasting ability (spell save DC 17).

3/Day: Conjure Animals at 7th level (but only conjuring 24 lizards, 24 flying snakes, 24 poisonous snakes, 12 crocodiles, or 3 giant constrictor snakes)

Absorb Elements. The dragon can cast absorb elements as if at 4th level as a reaction.

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.

Move. The dragon can move up to half its flying speed without provoking attacks of opportunity.