Aurinax, Gold Dragon Lord

Amphibious. The dragon can breathe air and water.

Colossal. The dragon is one size category bigger than Gargantuan.

Innate Spellcasting. The dragon’s spellcasting ability is Charisma (spell save DC 27, +19 to hit with spell attacks). The dragon can innately cast the following spells, requiring no material components:

At Will: Bless, Comprehend Languages, Detect Evil and Good, Detect Magic, Detect Thoughts, Mage Hand (the hand is invisible), Thaumaturgy, Zone of Truth

3/Day Each: Cure Wounds, Dispel Evil and Good, Geas, Heal, Slow, Suggestion, Word of Recall

1/Day Each: Commune, Plane Shift, Revivify

Keen Detection. The dragon has advantage on all Wisdom (Perception) skill checks.

Legendary Resistance (5/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Magic Weapons. The dragon's attacks are considered magical.

Siege Monster. The dragon deals double damage to objects and structures.

Unusual Nature. The dragon does not require food or drink.

Multiattack. The dragon can use its Frightful Presence. It then makes four attacks: one with its Bite, two with its Claws, and one with its Tail.

Bite. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 23 (2d12 + 10) piercing damage plus 9 (2d8) fire damage.

Claw. Melee Weapon Attack: +19 to hit, reach 15 ft., one target. Hit: 19 (2d8 + 10) slashing damage. On a hit, if the target is size Huge or smaller, it is grappled (escape DC 27) and is restrained until this grapple ends. The dragon has two claws, each claw can grapple one target at a time.

Tail. Melee Weapon Attack: +19 to hit, reach 25 ft., one target. Hit: 21 (2d10 + 10) bludgeoning damage. On a Hit, the target must succeed on a DC 27 Strength saving throw. On a failed save, the target is knocked prone. If a target fails its saving throw by 5 or more, it is also pushed up to 60 feet away from the dragon. If a pushed target strikes a solid surface, the target takes 3 (1d6) bludgeoning damage for every 10 feet it was pushed. If the target is pushed at another creature, that creature must succeed on a DC 27 Dexterity saving throw or take the same damage and be knocked prone.

Fire Breath (Recharge 5–6). The dragon exhales a blast of fire in a 300–foot cone. Each creature in that area must make a DC 27 Dexterity saving throw. On a failed save, a creature takes 90 (20d8) fire damage. On a successful save, a creature takes half as much damage.

Weakening Breath (Recharge 5–6). The dragon exhales gas in a 150–foot cone. Each creature in that area must succeed on a DC 27 Strength saving throw. On a failed save, a creature has disadvantage on Strength-based attack rolls, Strength checks, and Strength saving throws for one hour. A creature weakened in this way can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Frightful Presence. Each creature of the dragon's choice that is within 300 feet of it and is aware of the dragon must succeed on a DC 27 Wisdom saving throw. On a failed save, a creature is frightened of the dragon for one minute. A frightened 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.

Change Shape. The dragon magically transforms into any Beast, Giant, or Humanoid that is size Huge or smaller, while retaining their game statistics (other than their size). This transformation ends if the dragon is reduced to 0 hit points or uses a bonus action to end it.

Draconic Dash. While the dragon is flying or swimming it can take the Dash action as a bonus action.

Radiant Claw. As a bonus action, the dragon’s claws glow with a deadly bright golden light in a 30–foot–radius sphere and dim light for an additional 30 feet. The dragon’s claws glow with this radiant energy until the end of its next turn or until it hits a target with a Claw attack. The next time the dragon hits a target with one of its Claw attacks while they are glowing, the attack deals an additional 22 (4d10) radiant damage. If the dragon hits a Fiend or Undead with this attack, the target takes an additional 11 (2d10) radiant damage.

The dragon can take 5 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 each of its turns.

Attack. The dragon makes a single Claw or Tail attack against a target within reach.

At Will Spell. The dragon casts one of its “At Will” spells, from its Innate Spellcasting list that has a casting time of one action.

Detect. The dragon makes a Wisdom (Perception) check.

Shattering Roar (Cost 2 Actions). The dragon unleashes a thunderous roar. The roar is audible out to 5 miles. Each creature within a 40–foot cube originating from the dragon must succeed on a DC 27 Constitution saving throw. On a failed save, a creature takes 36 (8d8) thunder damage and is deafened until the end of its next turn. On a successful save, a creature takes half damage and is not deafened.

Wing Attack (Costs 2 Actions). While in dragon form, the dragon can beat its wings. Each creature within 30 feet of the dragon must succeed on a DC 27 Dexterity saving throw. On a failed save, a creature takes 19 (2d8 + 10) bludgeoning damage and is knocked prone. The dragon can then fly up to half its flying speed.