Adult Iron Dragon

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.

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

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

Bite. Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: 22 (2d12 + 9) piercing damage.

Claw. Melee Weapon Attack: +15 to hit, reach 5 ft., one target. Hit: 18 (2d8 + 9) slashing damage.

Tail. Melee Weapon Attack: +15 to hit, reach 15 ft., one target. Hit: 20 (2d10 + 9) bludgeoning damage.

Draconic Forge. (Recharge 5-6). The dragon exhales molten iron and forges armaments meant to aid it. Roll a 1d4 and the dragon gains one of the following for the rest of the combat, it can only benefit from each option once.

1. The dragon creates a melee weapon it becomes proficient in, this weapon replaces its bite, claw or tail. Dealing an additional 1d12 piercing damage and considered magical for the purposes of bypassing resistances.

2. The dragon creates a ranged weapon it becomes proficient in, this weapon replaces its bite, claw or tail. It has a range of 60/120ft and is considered magical for the purposes of bypassing resistances.

3. The dragon creates armor it immediately dons. Gaining a bonus to its armor class equal to 2.

4. The dragon creates a shield it immediately dons. Gaining a bonus to its armor class equal to 2.

Draconic Surge. (Recharge 6). The dragon inhales, suddenly unleashing it's battle prowess. On its turn it can take an additional action.

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.

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

Tail Attack. The dragon makes a tail attack.

Wing Attack (Costs 2 Actions). The dragon beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 18 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. The dragon can then take an attack at a target within range.