Ancient Moonsilver

Cosmic Nature. Moonsilver does not need to eat, drink, breathe or sleep as long as it is in natural light (sunlight, moonlight).

Legendary Resistance. (3/day) If Moonsilver fails a saving throw, it can choose to succeed instead.

Limited Telepathy. Moonsilver can magically transmit simple messages and images to any creature within 60 feet of it that can understand a language. This form of telepathy doesn't allow the receiving creature to telepathically respond.

Magic Resistance. Moonsilver has advantage on saving throws against spells and other magical effects.

One With Magic. Moonsilver can cast all spells from the Wizard spell list at will with no material components needed.

Multiattack. Moonsilver can use Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +6 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing damage.

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.

Claw. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 17 (2d6+10) slashing damage.

Comet Azure. Ranged Spell Attack: +17 to hit, range 300 ft., one target. Hit: 62 (8d12+10) force 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 21 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.

Magic Breath (Recharge 5-6). Ranged Spell Attack: +13 to hit, range 90 ft., two targets. Hit: 87 (14d10+10) force damage.

Spellcasting. The Ancient Moonsilver casts one of the following spells, using Intelligence as its spellcasting ability (spell attack modifier +19, spell save DC 27):

At Will: All spells from the Wizard spell list.

Enter the description for how bonus actions work for your monster here.

The Ancient Moonsilver 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 Ancient Moonsilver regains spent legendary actions at the start of its turn.

Comet Azure (Costs 3 actions). Moonsilver shoots a Glintstone Comet.

Detect. Moonsilver makes a Wisdom (Perception) check.

Tail Attack. Moonsilver makes a tail attack.

Wing Attack (Costs 2 actions). The dragon beats its wings. Each creature within 10 feet of the dragon must succeed on a DC 22 Dexterity saving throw or take 15 (2d6 + 10) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.

Enter the description for how mythic actions work for your monster here.

Mythic Action Name (Costs # Actions). Enter the description for your mythic action.