adult Iron Dragon

Legendary Resistance (2/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Rusting scales. If any metal comes in contact with the scales, the object rusts.

Metal sense. The dragon can sense any metal within 50ft of it.

Multiattack. The dragon makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 15 (2d10 + 2) piercing damage.

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

Tail. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 14 (2d8 + 2) bludgeoning damage.

Rusting Breath (Recharge 4–6). The dragon exhales rusting gas in a 60-foot cone. Each metal object in that area rusts.

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.

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.